IMPORTANT:

This is your final exam.

You have 60 hours.

Your solution must at least allow Harry to evade immediate death, despite being naked, holding only his wand, facing 36 Death Eaters plus the fully resurrected Lord Voldemort.

If a viable solution is posted before *12:01AM Pacific Time* (8:01AM UTC) on Tuesday, March 2nd, 2015, the story will continue.

Otherwise you will get a shorter and sadder ending.

There are more details and suggestions at the end of the chapter.

Question for Eliezer: Would a post to a LessWrong HPMOR discussion thread count as a solution, or must all solutions be posted to fanfiction.net?

A transfigured port key in his glasses does seem possible, or some kind of explosive device hidden in the transfigured ring.

EDIT: Fawkes is also a way out here, if Harry can delay an enemy attack for several seconds

Second edit (the serious one): The ring contains some kind of binding device. This could be the blinding potion Harry used in battles, a set of flash-bang grenades, or (most likely) a seventh-year variant of the blinding potion Harry bought off a student. This countermeasure will blind the unwarded death eaters which allows Harry to immediately fall to the ground and call Fawkes. Fawkes teleports Harry out and allows escape.

Disappointing. It appears as though Eliezer wrote himself into a corner, and is now looking for help from the readers...

Beneath the moonlight glints a tiny fragment of silver, a fraction of a line... (black robes, falling) ...blood spills out in litres, and someone screams a word.

I'm relatively confident that this quote is a part of the solution. Maybe Harry partially transfigures a monofilament blade and starts cutting down everything.

If you can think of any trick that I have missed in being sure that Harry Potter's threat is ended, speak now and I shall reward you handsomely... speak now, in Merlin's name!"

Voldemort forgot a very basic ”trick”: disarming Harry first.

At the end of chapter 112, we wondered about that, too. It turns out that Harry needed to have the wand to perform the vow. With that out of the way … why does Harry still have his wand? Is this just because Eliezer wants to make sure that Harry still has a way out? Or is there some in-universe reason for Voldemort to allow this?

Question for EY:

In the chapter, you wrote:

If a viable solution is posted before 12:01AM Pacific Time (8:01AM UTC) on Tuesday, March 2nd, 2015, the story will continue.

Does this mean that the reader-suggested solution will in fact be used, or will the story simply continue with the solution you originally had in mind?

After 5 minutes of thinking about it, the only thing I could come up with concerns:

"HE IS HERE. THE ONE WHO WILL TEAR APART THE VERY STARS IN HEAVEN. HE IS HERE. HE IS THE END OF THE WORLD."

Bellatrix and Sirius are stars, and also Death Eaters. Voldemort has already torn apart Bellatrix to use the Dark Mark, and Harry can tear apart Sirius with the Partial Transfiguration trick people are talking about. How do we know Sirius is present? Because there is a Death Eater named "Mr Grim" who is stated to have known the Potters.

Hang on, isn't Sirius in Azkaban?

"I'm not serious, I'm not serious, I'm not serious..."

The "he" refers to both Tom Riddles, as they are branches of the same person.

Troubles with this suggestion:

The "HE IS THE END OF THE WORLD" part remains unresolved.

Narratively unsatisfying.

Not a solution, but should the Death Eaters be discounted as not good for much of anything?

I don't just mean that Voldemort has shown them to be fairly incompetent, but that they may be too shaky to use whatever remains of their skills.

As an orthodox Discordian, I would be very pleased if it turned out that one of the Death Eaters has an idea which would be very useful for Voldemort, but is too afraid to say it.

Lets see..

Notes: EY didn't say that noone was aware of what was happening, just that anyone who would help Harry think he is at the game. Given the prophecy about Harry, this has disturbing implications.

Anyway: Obstacles: 39 minions in not-defensively enchanted blacks. One dark lord who can't use magic on you, but who can shoot your ass, An absolute prohibition on moves that could escalate to world threatening levels.

Assets: Naked pasty english lad. Wand. Parseltongue.

.. You know, normally in this sort of situation I'd recommend talking. Parseltongue is far and away the most potent tool he has, because he can tell Voldemort true things, and Voldemort will not be able to scoff at him.

But the problem is, the only things Harry could tell him that would make him delay killing him are things Voldemort should not be told, even at the cost of his life.

So combat it is.

Sigh. This is going to hurt.

Cant partially transfigure air, but wands are not indivisible objects, so he still has a small amount of material to work with, at least once.

Partially transfigure the tip of the wand into photons. The kind of flash of light that leaves burns. Everyone is looking at you - And now they are all blind. Possibly also on fire. Do it with the center of the tip so that you are in the shadow cast by the wand - but expect a hospital stay. And a need for a new wand. Primarily, the point is that this will attract attention. Most likely, timeturned attention. So if you do this, there is now a reason for someone to rescue you a faction of a second after the initial flash. .. Which shouldn't actually even be necessary. If I read Voldemort correctly, he will bail if actually hurt. Certainly since he has already extracted the wow...

Is Voldemort familiar with logical syllogisms? If not, it should be possible for Harry to trick him by saying something that seems to imply something else, without actually confirming the second thing as true, a la Chapter 49:

Harry kept his face steady. "I was looking up some facts about the Patronus Charm earlier," he said. "According to The Patronus Charm: Wizards Who Could and Couldn't, it turns out that Godric couldn't and Salazar could. I was surprised, so I looked up the reference, in Four Lives of Power. And then I discovered that Salazar Slytherin could supposedly talk to snakes." (Temporal sequence wasn't the same as causation, it wasn't Harry's fault if Professor Quirrell missed that.) "Further research turned up an old story about a mother goddess type who could talk to flying squirrels. I was a bit worried about the prospect of eating something that could talk." (emphasis mine)

One possible example proposed in a review on fanfiction.net (and the one that set me on this train of thought in the first place) is, "If you kill me, the world will end." Since the world will end no matter what, the consequent is guaranteed true, making the content of the antecedent irrelevant due to contrapositive shenanigans... but Voldemort doesn't know that, and it sounds like the end of the world is dependent on Harry's death.

The Parseltongue statement must be a critical part of the upcoming solution, I think. Simply killing the Death Eaters will not do; they are, as Voldemort puts it, useless. (That is, a solution that disables the Death Eaters but not Voldemort is not a solution.)

The text of the boundary conditions suggests that Harry can't change Voldemort's values, but the lesson suggestion makes clear that he can change Voldemort's beliefs.

I think the first thing for Harry to suggest is that the prophecy is being misinterpreted. The trouble with this is he needs to hear the prophecy to argue it as well as possible, and Voldemort is unlikely to tell it to him.

So, what lessons does Harry have for Voldemort? Partial transfiguration, and implicitly timeless physics. Friendship? Science fiction? Dyson spheres? We, with knowledge of the prophecy, can feed Voldemort the data he needs to come to the right conclusion.

(During these discussions, of course, he can be partially transfiguring whatever he likes. Carbon nanotubes, hollowing out the ground beneath him, and so on.)

(Edited to remove less interesting solutions)

• Harry can tell Voldemort that Harry's death has an unknown chance of hijacking Voldemort's horcrux network, and neither of them have enough information to push that probability below 5%. As far as I can tell, that's simply true. We know that Voldemort hasn't done any tests of the improved horcrux spell until now, and has been mistaken before about its working. The Voldemort described in this chapter would not accept a 5% risk on this particular plan, so he will carry out some experimental tests before killing Harry. That seems to allow Harry to evade immediate death, which is what Eliezer asked for.

• Harry's death burst will very likely interact with Voldemort's magic anyway, like the wards Voldemort placed around the spot, or the dark marks on minions' hands. That changes the whole plan. Now Voldemort must get himself and the minions far away at the moment of Harry's death, and also lift the wards. That buys some time as well, and is compatible with the previous idea.

• Voldemort has just taught Harry how to un-transfigure stuff wandlessly. If Harry's glasses are some sort of transfigured distraction that could be used to buy a couple seconds, Harry could use it, and immediately fire Flitwick's swerving hex. I'm pretty sure Voldemort doesn't know about that one, can't dodge because the hex was fast enough to drop Moody, and can't shield because that would count as magic touching. (Moreover, even if Voldemort dodges, the hex might still touch his wards around the graveyard, so maybe Harry can just fire in a random direction.) That could be one way to cause a resonance cascade, what happens next is anyone's guess.

ETA: I just posted a more fleshed out solution on /r/hpmor. It's very likely that it can be improved even further.

If knowledge of the True Patronus can prevent people from being able to cast Patronus 1.0, is there a way for knowledge of the True Patronus to harm Voldemort?

I've seen it on a couple of other comment threads, but I think that Harry's understanding of time-causality is key here. If the lesson of the Comed-Tea is learned, it seems that efforts to defy prophecy are useless from the get-go.

But then I'm not practiced at arguing time-travel mechanics - can anyone else elaborate on this question?

Harry is allowed to solve this problem any way YOU would solve it. If you can tell me exactly how to do something, Harry is allowed to think of it.

This is not quite phrased correctly. While I know less magic than the protagonist (having not attended Hogwarts for a year), I know far more physics and mathematics than he does. I am also privy to world-building knowledge that he isn't. For example, we know about major artefacts:

• The Elder wand has been repeatedly featured in the fic, but neither Harry!Riddle not Voldemort!Riddle are aware of it yet.

We also know little trivia:

• Tom Riddle's middle name in this AU is Morfin, not Marvolo. Knowing canon this tells us something about Merope Gaunt's relationship with her father and brother.

In conclusion: it's not enough for us to think of a solution, we also need to explain how Harry can think of it. There's no point in simulating Harry's smarts on my hardware, I can use my own smarts. But I do need to simulate Harry's knowledge.

If you have any remotely good idea, post it as a fanfiction.net review. The currently extant ones are awful. Most don't even make sense.

Important: QQ's earlier parseltongue-spoken plans for Harry to become ruler of the world were said before he heard the 'tear apart the stars' prophecy. So it appears V changed his mind after hearing the prophecy.

This is very similar to a solution I published earlier, except that when I first proposed it, I had forgotten that Harry hadn't got his wand at that point in time (but why hasn't he been disarmed now?).

The one plausible power Harry has is transfiguration, seeing as there are no dementors nearby, it seems unlikely that the patronus 2 can be used as an offensive weapon against anything apart from dementors.

Harry should transfigure some exotic matter with density far in excess of normal matter, and use it to slice through all the death eaters and Voldiemort. Since it has been established that you can transfigure against tension, he doesn't even need to move his hand to wield this weapon: the power of transfiguration can move it around in a circle.

I'm guessing this exotic matter will be silver in colour:

Beneath the moonlight glints a tiny fragment of silver, a fraction of a line... (black robes, falling) ...blood spills out in litres, and someone screams a word.

As for what type of exotic matter, tau particles, top and bottom quarks are all extremely unstable. This might not matter, because if transfigured into parts of particles, perhaps they would be stable, in the same way that free neutrons are not stable but nuclei are, although a google search seemed to indicate that muonic atoms are stable iff they are electron degenerate. But for that matter, I don't even know if stability applies to objects that are being transfigured.

A second concern is the hypothosis that strange matter is more stable than normal matter, and thus a stranglet would consume the earth. I don't know if this hypothosis was around in 1992, or whether Harry would have heard of it. If this does occur to him, then it might block the use of strange quarks. But I presume charm quarks are ok.

I think transfigureation is silent, and does not involve wand movements, rather the wand has to be kept stationary and in contact with the object, so it will not warn the death eaters and give them a chance to strike. The material to be transfigured could be part of the wand, or an outer layer of Harry's skin.

What are the other possibilities?

Someone else suggested that partial transfigureation could be used as a cutting weapon. I imagine it would be stopped by sheilds, but I suppose its possible.

Transfigured normal matter, including carbon nanotubes, would not be able to penetrate sheilds (in fact, carbon nanotubes have low sheer strength, so they would make very poor cutting implements).

What else is silver? The patronus can be willed to take the form of a sphere, so presumably it could be willed to take the form of a blade. But something powered by life should not be able to kill, even if it could penetrate sheilds. The dark patronus? Fulled by the desire to stop the death of those you love by killing those you hate?

Unicorn's blood? Hermoine the alicorn princess's blood? Doesn't seem like an effective weapon.

Could an extremely thin steel wire penetrate matter by partially transfigureing its way through, and penetrate shields by going underground, and coming up through the feet? Can sheilds defend against attacks from below, or do they cut off at the ground?

EDIT: The exotic matter weapon will be very small so perhaps no death eater will see it. To buy time to think, or for the transfigureation to work, Harry might need to start giving Voldie useful information, such as the patronus, which he can truthfully point out poses no threat to Voldie, because Voldie can't cast patronus v.1. Awaking Hermione, or causing a resonance cascade with Voldie could cause a distraction. Possibly Harry could come back from one hour in the future to help the battle, although we now have a situation where Harry survives, but only if he survives, and I'm not sure about how causial loops are supposed to work. For that matter, future surviving Harry could have brought the cavalry back in time with him, if this wasn't explicitly forbidden.

EDIT 2: Magnetic monoples might be the best shot, although this would be thin enough to be invisible, not silver. http://www.orionsarm.com/eg-article/48630634d2591

Harry can test the limits of Parseltongue's truth detection properties. "I am plugged in to your Horcrux network and will not be stopped by killing me now."

Interesting, so it all comes down to a version of the AI box experiment.

"Expecto Patronum", at which point Death-Eaters will fire an utterly futile barrage of AKs. Voldy still can't fire directly at Harry due to resonance. Gun is not as much concern if you move fast enough and considering Voldy is some distance away. Gives Harry enough elbow room to get to his nearby (?) Pouch, Cloak and Time-Turner with 1 more hour on it. At this point we're sorta free of any serious constraints.

Thoughts:

• Apparate away
• Turn wand into portkey to somewhere far away
• Cast an undodgeable spell at Voldemort, force magics to interact.
• Should have previously created a dead-man's switch. Still could transfigure something to serve as such, but not many good choices. Antimatter possibly blocked by Vow, toxins can probably be easily contained.
• There are some more mundane combat options given that Death Eaters aren't exactly the quickest to adapt and Voldemort can't use magic on him. Transfiguring body parts of Voldy or death eaters into a combination of high-pressure gas and a toxin or other agent may work. A particular mundane strategy is Ascendio->Transfigure Voldy's brain into high pressure hydrogen sulfide->create portkey in confusion. Or Ascendio->accio time turner from pouch-> take further action.
• There are a few other options that unlock if Harry tries to, say, teach Voldy Patronus 2.0. Voldy has to mentally engage with the task which is likely to result in a loss of reaction time.

(EDIT: I thought about this some more, produced a better solution, submitted it as a review, and also posted it here)

1. Voldemort knows that Harry possesses an altered version of the Patronus spell, and something else that affects dementors, but not the spell's nature. Harry can buy time by offering to explain how these work, by doing so, and negotiating for more names. Harry can truthfully say that learning certain things about the Patronus and about Dementors will have side-effects that Voldemort may not want, and that this means he needs to think about what to say. Voldemort will surely exert time pressure, but can only speed this up by so much if he wants to fulfill his goal of gaining all of Harry's secret powers. He can also try to convince Voldemort to let him cast his modified patronus; this is very unlikely to work, but should be done anyways because seeming to not try any tricks would itself be suspicious.

2. A winning strategy should simultaneously disable all of the death eaters present and Voldemort himself. Voldemort will be disabled if their magics touch, especially if that touch can be sustained.

3. The main weapon at Harry's disposal is partial transfiguration. I spoke first of buying time, because we also know that transfiguration takes time, although we don't know all the details of how the time requirement is determined or where in the process there is first external evidence of a transfiguration in progress. Harry has already practiced transfiguring thin cross-sections through things, and used this power in anger twice (in Azkaban and against the troll), so he should know what he can do there, how long it will take, and when it will become visible.

4. Harry can only transfigure something that touches his wand. So he transfigures a narrow segment starting at his wand, passing through himself into the ground, and proceeding from there.

5. Since one turn of Harry's time turner remains, if a plan ends with Harry recovering his items, then there may be an extra invisibility-cloaked, fully equipped copy of him nearby. While there is a charm that Voldemort could have cast which would detect if that were so, we don't actually see him cast it. However, the resonance effect would reveal his presence; so instead, if Harry manages to time turn and escape, he should immediately contact and lend his cloak to Mad-Eye Moody.

6. If Harry can get a partial transfiguration off, there are a ton of possibilities. Harry has recently learned how, in a complex transfiguration, to control the order in which parts appear. So these options are not mutually exclusive; he can perform several or all of them at once.

   • There is a time turner nearby, in a pile of objects on the floor which no one is paying much attention to. He can modify the floor under it, flipping it over.
   • There are objects transfigured by Voldemort nearby (false teeth), in the same pile; if Harry's transfiguration touches one of them, it could cause resonance. Many of the other objects in that pile will also be enchanted by Voldemort's magic; transfiguring the entire surface underneath the heap would strengthen the effect. (This is important because Harry's transfiguration can't reach Voldemort himself, since Voldemort isn't touching the ground).
   • There is a Hermione horcrux nearby, which activates by touch. What "touch" means in the context of partially-transfigured cross sections has not been nailed down, but if that does count, then Harry can cause the hermione horcrux to simultaneously touch all of the death eaters. Furthermore, he can cause it to not simultaneously touch himself, by transfiguring a bit of floor into a delay switch, and lifting up his foot after the transfiguration is complete.
   • There are weapons Harry can make with low volume and low mass. If the configuration is not too complex for the time available, he could try transfiguring a cross-section that passes through the brains of each of the death eaters.
   • Hermione is nearby, asleep. She will wake up if a little bit of her skin turns into acid.

Ideally, he would do all of these things as part of the same transfiguration; but that might be too much.

(Not a serious suggestion)

Using the Axiom of Choice and partial transfiguration, Harry divides himself into two exact copies, one of which is killed by the Death Eaters and the other of which escapes.

I think a big question here is "what kinds of magic, if any, are available?". Answer might be "none". Partial transfig takes too long, everything else requires motion.

That seems to leave to possibilities:

• Realizations that allow for re-access to magic
• Talking your way out of it

In other words, no known magic is useful in this situation.

Does that seem reasonable? Does anyone remember a form of magic that doesn't require motion or time?

I made a countdown timer.

We know that previous attempts by Voldemort to thwart a prophecy have backfired horribly. It therefore seems reasonable to assume that prophecies in HPMoR (as in canon) are self-fulfilling. (Warning: TVTropes-link!)

I therefore predict that Voldemort’s efforts to thwart this prophecy will counteract that intention and lead to the fulfillment of that same prophecy.

Thoughts:

• Can the unbreakable vow be leveraged for unbreakable pre commitments?
• Harry knows that the horcruxes will eventually be destroyed through heat death of the universe if nothing else and could use this to tell Voldemort something like "if you kill me you will die" in parseltongue

(Plausible) Harry can stall for time by explaining his discovery of Mendelian magical inheritance, and the implication that magic is not a property of Wizards but rather bestowed upon them, possibly by the Atlantean Matrix lords. This is a power, or at least knowledge, the Dark Lord knows not, and it gives him time to do his Partial Transfiguration attack, while also not giving Voldemort any kind of immediate strategic advantage.

(Implausible) This would then segue into a discussion of whether Voldemort is just seeing his CEV, and simulated-Harry trying to break it. Somehow, they end up breaking the Mirror's illusion, thus destroying this "world".

Posting write-only. EDIT I am no longer write-only

Recall Harry's transfiguration power:

Last week, when the graduating Ravenclaws were discussing their N.E.W.T. scores, Harry had overheard that upper-year Transfiguration practice involved several 'shaping exercises' that relied more on control and precise thinking than raw power; and Harry had promptly set out to learn those, whacking himself hard on the forehead for not trying to read all the later-year textbooks earlier. Professor McGonagall had approved Harry doing a shaping exercise that involved controlling the way in which a Transfiguring object approached its final form - for example, Transfiguring a quill so that the shaft grew out first, then the barbs. Harry was doing an analogous exercise with pencils, growing out the lead first, then surrounding it with wood and finally having the eraser form on top. As Harry had suspected, focusing his attention and magic into a particular part of the pencil's ongoing transformation had proven similar to the mental discipline used in partial Transfiguration - which could indeed have been used to fake the same effect, by partially Transfiguring only the outer layers of the object. This way was proving relatively easier, though.

With this Harry can:

• Partially transfigure his leg into a winding worm. With this leg-worm he could:
  • Touch his transfigured self to Voldemort's magic, thereby causing Voldemort to collapse.
  • Seek out the time-turner . Since the leg is part of his body, twising the time turner would make him go back in time. This is a win, if none of the Death Eaters have cast anti time-turner charms, and Voldemort hasn't either. The death eaters haven't had much time and were immediately given orders. It is unclear if Voldemort would cast wards that could interact with Harry.
• Transfigure all of himself into the adult form of Voldemort and give counter orders. "That's Mad-eye Moody, you nitwits!"
• Partially transfigure his nose to cover his mouth, then cast non-wordless spells

Dumbledore can cast the Patronus wordlessly (chapter 57). Maybe Harry can too, and

• will the Patronus to cover his body (as seen in chapter 100)
• will the Patronus to charge Voldemort
• will the Patronus to Hug Voldemort, changing his utility function with the unknown power...of love!

Of course, there are lots of solutions if you allow Harry to have done stuff off-camera. "Cedric, if I don't meet you at 11:59 tonight carrying a mayonnaise-infused gerbil, please use your time turner to cause a paradox". Harry could turn into his hitherto unseen animagus form ETA which might be a peregrine falcon, the fastest of birds.

And the rest of you, you must fire if Harry Potter tries to run, even if it means striking at your fellow Death Eaters.

Useful

Harry's assets:

• Glasses - probably a distraction, but could be just about any nonhuman object, transfigured.
• Cedric - probably in the mokeskin pouch, not easily accessible, probably only useful as a human shield, which is not Harry's style
• Invisibility cloak - might be able to block the Killing Curse, useful in general, Harry is the Master of this Deathly Hallow, it's plausible but unlikely that he'd be able to Call it without words or gestures.
• Voldemort's bargain - Voldemort has promised in Parseltongue to protect one person for each power Voldemort knows not that Harry names.
• Partial transfiguration - both a Power Voldemort Knows Not and a tactical tool
• Wand
• Harry's own flesh (which he can use for partial transfiguration)
• The air
• The death eaters (including their robes, their bones, etc.)
• Sirius ("Mr Grim")
• Stuporfy

Foreshadowing / prior hints of resources:

• Thick/heavy enough physical objects can block curses aside from the Killing Curse
• Resonance between Harry's and Voldemort's magic more likely to harm/incapacitate Voldemort than Harry
• Harry was instructed by Voldemort to cast Mahasu on any student in the classroom, chose himself. Foreshadows choosing to use promise of protection on himself?
• Antimatter was mentioned earlier, Voldemort may not know enough about it yet.
• Hermione transfigures a Buckytube
• Use of Muggle devices
• Harry's prior weakness is that he doesn't ask others for help
• Harry decided to accept the idea that the air can't be transfigured before he figured out the insight necessary to do partial transfiguration, this could be wrong, the air as well as his flesh could be transfigurable
• Prophecy about tearing apart the very stars (meaning Sirius and Bellatrix and Draco?)

Harry had to remove his left shoe, and take off the toe-ring that was his emergency portkey if someone kidnapped him and took him outside the wards of Hogwarts (and didn't put up anti-Apparition, anti-portkey, anti-phoenix, and anti-time-looping wards, which Severus had warned Harry that any inner-circle Death Eater would certainly do).

That seems to rule out apparition, portkeys, phoenixes, and time looping, so transfiguring a time turner into his hands is out, as is trying to get into a Phoenix frame of mind to summon Fawkes or another phoenix to send a message, or using his portkey.

"There are desks which are heavy enough to be fatal if dropped from a great height. There are chairs with metal legs that could impale someone if driven hard enough. The air in this classroom would be deadly by its absence, since people die in vacuum, and it can serve as a carrier for poison gases."

Harry had to stop briefly for breath, and into that pause Professor Quirrell said:

"That's three. You need ten. The rest of the class thinks that you've already used up the whole contents of the classroom."

"Ha! The floor can be removed to create a spike pit to fall into, the ceiling can be collapsed on someone, the walls can serve as raw material for Transfiguration into any number of deadly things - knives, say."

"That's six. But surely you're scraping the bottom of the barrel now?"

"I haven't even started! Just look at all the people! Having a Gryffindor attack the enemy is an ordinary use, of course -"

"I will not count that one."

"- but their blood can also be used to drown someone. Ravenclaws are known for their brains, but their internal organs could be sold on the black market for enough money to hire an assassin. Slytherins aren't just useful as assassins, they can also be thrown at sufficient velocity to crush an enemy. And Hufflepuffs, in addition to being hard workers, also contain bones that can be removed, sharpened, and used to stab someone."

By now the rest of the class was staring at Harry in some horror. Even the Slytherins looked shocked.

"That's ten, though I'm being generous in counting the Ravenclaw one. Now, for extra credit, one Quirrell point for each use of objects in this room which you have not yet named." Professor Quirrell favored Harry with a companionable smile. "The rest of your class thinks you are in trouble now, since you've named everything except the targets and you have no idea what may be done with those."

"Bah! I've named all the people, but not my robes, which can be used to suffocate an enemy if wrapped around their head enough times, or Hermione Granger's robes, which can be torn into strips and tied into a rope and used to hang someone, or Draco Malfoy's robes, which can be used to start a fire -"

"Three points," said Professor Quirrell, "no more clothing now."

"My wand can be pushed into an enemy's brain through their eye socket" and someone made a horrified, strangling sound.

"Four points, no more wands."

"My wristwatch could suffocate someone if jammed down their throat -"

"Five points, and enough."

"Hmph," Harry said. "Ten Quirrell points to one House point, right? You should have let me keep going until I'd won the House Cup, I haven't even started yet on the unaccustomed uses of everything I've got in my pockets" or the mokeskin pouch itself and he couldn't talk about the Time-Turner or the invisibility cloak but there had to be something he could say about those red spheres...

This vaguely suggests a few options:

• Harry could improvise a dark ritual to sacrifice some of his internal organs to "hire an assassin" (counting on some sort of magical healing afterwards).
• Susan Bones might also be in the pouch ("Hufflepuff [...] Bones"). Note that the real Susan Bones was not with the other students who encountered Snape in the corridor.
• Harry likely knows of some efficient poisonous gases, if he can hold his breath for long enough he can simply transfigure part of himself into one of these and wait for the Death Eaters to drop.
• Harry could somehow try to cast a spell on Voldemort to invoke the resonance, push him in a direction that disrupts the semicircle of Death Eaters.
• Harry could transfigure the air around him into a thick physical barrier that blocks everything except the Killing Curse.

Ignoring the gasps rising from behind him, Harry crossed the radius of the Patronuses, strode to a single pace from Death. Its unhindered fear burst around him like a whirlpool, like stepping next to the sucking drain of some huge bathtub emptying out its water; but with the false Patronuses no longer obscuring the level on which they interacted, Harry could reach the Dementor even as it could reach him. Harry looked straight into the pulling vacuum and -

the Earth among the stars

all his triumph at saving Hermione

someday the reality of which you are a shadow will cease to exist

Harry took all the silver emotion that fueled his Patronus Charm and shoved it at the Dementor; and expected Death's shadow to flee from him -

• and as Harry did that, he flung his hands up and shouted "BOO!"

The void retreated sharply away from Harry until it came up against the dark stone behind.

Harry can sort of wandlessly wordlessly cast something like a Patronus, he could try to do something like this to Voldemort.

Beneath the moonlight glints a tiny fragment of silver, a fraction of a line... (black robes, falling) ...blood spills out in litres, and someone screams a word.

This strongly suggests a Buckytube monofilament whipped around to decapitate all the Death Eaters. This is the most plausible solution, and it's somewhat compatible with the other Partial Transfiguration option, which is to tell Voldemort about it in exchange for protecting Harry's life (and to buy time). This is also compatible with Harry's glasses being a transfigured shield (or transfigured charmed magical shield, in either case there's no reason someone couldn't have just magically LASIK-ed his vision), which would give him a defense against any non-Killing Curse spells that go his way from anyone he doesn't immediately kill. Then he lunges for (or accios) the pouch and cloak, retrieving Hufflepuff (Susan) Bones and Cedric, to help him fight the remaining Death Eaters (or go for help). Then he casts a Patronus to get McGonagall (and insists she not disrupt the game).

Ah, better yet - the glasses should be his broomstick. Or his broomstick AND a shield. AND a gas mask. Fit together (since glasses are composite objects anyway).

OK, so here's the attack plan, to tear apart Voldemort's plan at every possible point of intervention:

1) While transfiguring a long buckytube monofilament out of his own flesh, tell Voldemort about partial transfiguration, demand that Harry himself be saved in return.

2) Wordlessly cast the Patronus at Voldemort to try to throw him off balance - as a bonus, if he manages a worldess wandless corporeal Patronus it can do step 5 early, OR possibly block a Killing Curse (not sure).

3) Whip the buckytube around to slice through a bunch of Death Eaters. Simultaneously, wordlessly wandlessly finite incantatem the glasses to detransfigure his broomstick.

4) Fly to (or accio while dodging curses) the pouch, extract Susan and Cedric, put on the cloak. They know from battle class that they should lift the sleep spell on their ally Hermione. (Harry shouldn't since it would be an interaction with Voldemort's magic that would be more likely to harm Harry than Voldemort.)

5) Cast a Patronus to get help from McGonagall (who can use her time turner so as not to disrupt the game), telling her to bring every competent battle mage she can get.

6) Cast Stuporfy at Voldemort to try and trigger the magical resonance, then fly straight at him to give him a hug.

Here's my idea, which I've posted as a review on FF.net. Harry has advanced transfiguration. The Philosopher's Stone can make transfiguration permanent. Harry can bring life to dead things. This is very close to Harry being able to create copies of himself, which would surely be attractive to Harry. The question, then, is; when did Harry first realize this capacity?The possibility of creating a body double might very well have been enough to have persuaded Dumbledore to let Harry use the Philosopher's stone, which he seems to have access to. Or Harry might have procured the stone himself, which he seems able to, intellectually. It's just a matter of procuring a confundus charm. The current Harry could have been memory-charmed into believing he was the original Harry and this ruse may have gone on for quite some time (though reviving Hermione would have made it obvious that he had this power, and I'm not sure if Harry would have demured to do so if he thought he could. I suspect he'd have to be persuaded by someone else.) It might help in explaining why Harry could attack Voldemort, since Voldemort's curse bound only Tom Riddles "descended from him", and the current double would have been "descended" from Harry.

In this case our Harry could be destroyed and another Harry would still live (and could even play off his surviving destruction as a type of magic, snapping his fingers.) Similarly, could Harry sacrifice one of his doubles to create a horcrux and then inhabit a spare transfigured body, laying in stasis somewhere (like his bag of holding?) This seems a bit dark for Harry, but maybe possible.

I'm not sure what the limitations on this type of duplication magic would be. Perhaps multiple Harrys would need to be created 'from hit points' and even if one Harry could make another they might each be weaker or draw on the original Harry's HPs. But an army of Harry Potters striding over the hill wouldn't be a bad solution to this problem. Chaos Army of One. etc.

It occurs to me that, given the philosopher's stone is around, any superweapons Harry could create and conceal with it in slightly under an hour could exist in the clearing, provided that they're enough to let Harry survive another hour, access the time turner, and create said superweapons.

Also, since prophecies are self-fulfilling and Voldemort prefers a world that won't end to a world that will and Harry has already made the appropriate unbreakable vow to do everything to prevent the end of the world, Harry could argue that expected universe where Voldemort lets Harry live is far superior to the one where Harry dies.

The case for thinking seriously about Partial Transfiguration:

1) Partial transfiguration is wordless, but wanded.

2) it's a power Riddle doesn't know as per the prophecy.

3) Harry still holding his wand is a Chekov's Gun for a wanded spell such as transfiguration.

4) Yes, that does seems too obvious, but I don't think Eliezer wants to end the story here so he wouldn't want an extremely subtle puzzle.

5) The only evidence against is that Quirrell might have ripped it from Hermione's mind...but he wouldn't know what to look for, would he? And Dumbledore may well have obliviated it away.

Constraints

1) Only very small amounts of matter can be transfigured

2) The want must not be raised, so Harry must transfigure the ground he's pointing at. No transfiguring people's bodies or anything fancy. The air can also be transfigured.

3) Outright explosives will kill Harry as well, so you can't just make a small patch of antimatter or airborne lethal toxin unless you can find a way to shield Harry.

So, guys - any ideas as to what thimbleful of tiny molecules, placed in the earth a few feet away from Harry, can save him?

EDIT: The case against partial transfiguration as a solution

1) Too obvious

2) Harry holding the wand not Chekov's gun. Riddle is aware that he aught to have disarmed Harry. Not disarming Harry means that somehow Riddle has contingency plans or even actively wants Harry to use the wand.

3) Any combat oriented action almost certainly involves death, regardless of head starts and discreteness, even if we manage to take down Riddle's current body.

I really do like dxu's "If you harm me greatly, the universe will end" or something similar in Parseltounge, though. (Since it will end with or without Harry's intervention, this is still true.) It seems the most elegant solution and would buy time to implement some other solution. hm. This system ate my previous post.

I'll have to rewrite it.

While this might be a little deus ex machina for Eliezer Yudkowsky, Harry can create a doppleganger of himself. He's recently learned more complex transfigurations. Dumbledore had access to the Philosopher's Stone, which could make such transfigurations permanent. Harry's special patronus seems to help the process in some cases. These are very complementary abilities.

If Harry could clone a copy of himself from a part of himself, and that copy could be made to forget it's origin then the captured Harry might not have to be the real Harry at all, and could be sacrificed. Harry could theoretically make an army of himself, even, and hide them in his bag of holding or some other place like a clown car. Further, Harry could clone himself and use that clone to make a horcrux gaining some kind of immortality without murder. I doubt that Dumbeldore would allow such dark magics, though.

Thought some more, and I have some ideas.

One of the realizations I think I had is that magic recognizes divisions where there are none. PT being the prime example, but also the ability of armor to block spells. PT relies on removing the caster's understanding of divisions; what if there is a way to add divisions? If Harry can convince himself that his skin is not part of himself, will it block spells the way thick leather does?

Conversely, are there other divisions that open possibilities if removed? Like between people and the ground, or people and people?

Most thinking I'm reading about uses PT to create a weapon with which to attack, but attack is not the goal. Escape is. Means of escape fall into a few categories, I think: Figuring out something like Apparition on the spot, quantum tunnelling, or Newtonian. Right now I'm just going to think about "newtonian" - It's just as ridiculous for transfiguration to not include velocity as it is for it to only effect "discrete" objects. Can Harry simply add enough velocity to himself to escape? (Adding acceralation doesn't work, as enough to escape fast enough probably squishes him)

Here are crazier things:

• There's good proper acausality in this universe. Coma-tea, time-turners, and the Stars spell. What's going on there? Is there some way to use that?

• At first, there is evidence that changes to the body and brain effect the mind. But, there's also a pile of evidence that, under circumstances, it doesn't - Horcurxes, and both resurrections. What if Harry can detach his life/magic from his body?

Harry obviousely needs to buy some time, so he'd better start speaking. Patronus V2.0 grants only the "good" kind of power and feeds on caster's maxHP, so it could be revealed easier than partial transfiguration. Some meaningful amount of time is going to be acquired (while explaining HPJEV's viewpoint) that way, because HPJEV and LV oppose death in entirely different ways (one wants to fight it and the other one flees). But that's too easy and either is not in the solution at all or is followed but something more clever.

By the way, nobody said that that quote about falling black robes was from the good ending. Nor we have a 100% proof that Patronus V2.0 blocks any AK: it could be only LV's AK, due to resonance.

Also, assuming that both HPJEV and Hermione survive with their memories intact and have a chance to talk, it's going to be very awkward. Being murdered by LV can be expected, at least, but it's not easy at all to tell Hermione that she has just been brutally resurrected with at least three Dark rituals, has her mind state constantly backed up to a Dark item and regereneration ability similar to the one of the weapon which killed her in the first place.

Why doesn't LV tell one of the DEs to finite incantatem HP's glasses?

Re-reading the story, this made me smirk in light of recent revelations:

Harry scowled at her. "Fine, I won't bite anyone who doesn't bite me first."

Harry might not be able to transfigure air into solid objects, but he can still transfigure air into other gases, right?

Even if the Death Eaters' masks had some kind of air filter enchantment on them, they likely don't anymore:

We... we were not fighting in them, Master, with you gone... so I did not maintain their enchantments...

So perhaps Harry could partially transfigure the air around the semicircle of Death Eaters into some highly toxic invisible gas while leaving enough normal air between the gas and himself that it would be slow enough to propagate that he would have time to deal with Voldemort and get away and/or diluted enough that it wouldn't incapacitate him?

HP should ask LV whether his robes are black and blue or gold and white.

But it does not serve as a solution to say, for example, "Harry should persuade Voldemort to let him out of the box" if you can't yourself figure out how.

It's a shame that nobody's going along this line of thought. It would be cool to see a full, successful AI-Box experiment out there as a fanfiction.

(I'd do it myself, but my previous attempts at such have been.... eheh. Less than successful.)

Planning thread over at /r/HPMOR for centralized discussion. It's probably better to have segregated groups working on this, but I don't really think that'll be a problem.

Obvious potentially useful moves:

• Buy time with discussion of secret powers (partial Transfiguration and true Patronus), since we're optimizing primarily for surviving the immediate situation and not for preventing Voldemort from knowing useful powers.

• Partially Transfigure himself in some useful way, depending on subsequent access to PStone to avoid T. sickness.

• Cast Patronus centered on himself to blind and to block AKs. (Problem: doesn't block other curses. But if he moves, Death Eaters might fire at the shiny thing instead of at him.)

• Un-Transfigure glasses into whatever emergency countermeasure Harry could have chosen. (Note: will still be stuck to Harry's face, so no bombs or suchlike.)

I've been primarily thinking along the lines of defense, escape, mobility. Once Harry gets to the Time Turner or the pouch he has more options.

ROT 13ed Final Exam suggestion:

Va Cnefyrgbathr "Jung cebonovyvgl qb lbh nffvta gb gur cbffvovyvgl gung V nz fhssvpvragyl Gbz Evqqyr gung V jvyy or pbcvrq vagb lbhe Ubepehk argjbex?"

Harry can also dispel any of his transfiguration wandlessly and wordlessly. So any toxic substance he creates he can dispel as it reaches him.

Voldemort might be failing to anticipate partial Transfiguration that has no visible effects (although it's unclear why Harry is allowed to hold the wand after the Vow is done). It might be Transfiguration of the tip of the wand or of a patch of own skin. Transfiguring it into carbon nanotube wires (Ch. 28) or something else super thin that's good at cutting things might make the result both deadly and invisible, while keeping the amount of stuff small in order to be able to complete the process in reasonable time (as with cutting the wall in Azkaban, Ch. 58). There is a problem with moving the Transfigured wires into place, but the "shaping exercises" (Ch. 104) might allow doing that using the process of Transfiguration itself (so that the original material might "grow spikes" that climb like vines over the area where the Death Eaters are standing and then rise up into place).

In Ch. 111 we see that it's possible to gradually break a Transfiguration (without a wand). This might gradually transform the wires back into a small object, cutting the Death Eaters into pieces in the process. The alternative ways of triggering the wires might be to yank them quickly enough; to prepare a simple contraption as part of the Transfiguration, to pull the wires without Harry's movement (a falling stone, if one is conveniently positioned, etc.); or to use the "shaping" process to perform the cutting movement as part of the Transfiguration itself. Possibility of some of these things depends on knowledge that Harry probably has, but readers aren't certain about.

If the hypothesis that magical resonance hurts Voldemort more than Harry is correct, the same action would also incapacitate Voldemort, countering superior magic. Anything less, like doing something to the gun, seems pointless, and magical resonance seems to be the only adequately strong available weapon, so this risk should be taken if there are no better alternatives.

This requires some time, so the first thing should be to start talking. It can't be about partial Transfiguration, but perhaps Dementors could be explained (even if this can't help Voldemort cast Patronus 2.0, maybe it can make him a master of the Cloak, or allow training a minion to cast Patronus 2.0). Another point that I don't see how to rule out is the possibility that Harry's death would send him into Voldemort's Horcrux network, which might harm Voldemort or lock him out. Discussing this might also buy some time, maybe a lot of time if Voldemort agrees that this is a serious risk that requires further study before Harry can be allowed to die.

If the move is successful, Voldemort needs to be incapacitated both inside or outside the Horcrux network, so the damage to the currently accessible body should be limited. It's still not clear that he can be incapacitated in a body, since he mentions ability to abandon a body at will (Ch. 107), but magical resonance might make him temporarily lose consciousness (evidence from Azkaban), giving time to put the body into some further containment. Perhaps he can be locked in with brain damage. I'd guess that Transfiguring Voldemort's body into something inert like a tree wouldn't stop the spirit from leaving it. Maybe if the body is surrounded by a sphere of material Transfigured by Harry, then magical resonance would prevent the spirit from escaping, though I don't see how we can expect this with any reliability, since the nature of this spirit thing is unclear. (Any solution to Voldemort containment that involves Transfiguration could be made to last with Philosopher's Stone, although applying the Stone to Harry's resonance Transfiguration should be first put to test, to check if the resonance remains intact.)

Following the principle that a disaster must be averted at every possible point of intervention, all these potentially useful measures should be applied at the same time. Even if the body is contained, Resurrection Stone and other horcruxes should be found and destroyed.

(By the way, tearing stars apart is just good sense, to use their matter and energy more efficiently. This might be a nice project to undertake sometime after defeating death and before the end of the world.)

Didn't V see at least the results of a Partial Transfiguration in Azkaban (used to cut through the wall)? Doesn't seem like something V would just ignore or forget.

Why hasn't Voldemort suspended Harry in air? He floated himself into the air as a precaution against proximity, line of sight problems, and probably magics that require a solid substance to transmit through. If Harry were suspended in air partial transfiguration options would be vastly reduced.

Why hasn't Voldemort rendered Harry effectively blind/deaf/etc. - Harry is gaining far more information in real time than necessary for Voldemort's purposes?

Also, it seems prudent not to let Harry get all over the place by shooting him, smashing him, etc. without some form of containment. I don't know how some part of Harry could cause problems, but it seems prudent to eliminate every part of him with Fiendfyre (blood, guts, and all) if that is what Voldemort is aiming for.

Can Fawkes be summoned to extract Harry? If it helps Harry can decide to go to Azkaban.

Harry should be aware that reality is basically doomed to repeat the Atlantis mistake by now (either via AGI or whatever Atlantis unlocked). With the vow that Voldemort made him take he can honestly say that he is the best bet to avoid that fate. That is, Voldemort now needs Harry (and Hermione) to save reality. This seems like the most straight forward method get out of the current annoyance.

Some partial transfiguration options I haven't seen mentioned: - Colorless / odorless neuro toxins (Harry should have researched these as he is in 'serious mode' now that Hermione died). Delivered via the ground directly into each death eater and/or into the air in specific areas. - Nanobots - I can't recall at this time if this would work or if Harry needs to have the design already in his head. It is possible Atlantis tech. may utilize a vast array of these already. - Transfiguration may allow one to exploit quantum weirdness. Many things can happen at very small scales that could happen at large scales if everything is lined up just so (which never happens in reality, but transfiguration may make possible).

I wrote a version of this up at reddit too, but it seems to me trying to hack the laws of physics is wasted effort when we know very little about how magic works in concrete terms. We don't know what Harry can really do, how fast he can do it, or whether Voldemort would notice.

What we do know are: * how Harry thinks * how Eliezer thinks * what Voldemort wants

So we should be looking at things Harry could say that would advance his goal of surviving rather than trying to come up with a combination of spells, with the understanding that winning ideas are probably going to cluster around narrative interventions that EY thinks are interesting or important. A few that spring to mind:

Memetic hazard: are there things Harry could say or bring to Voledmort's attention that would pose an existential risk to him if he harms Harry

Let the AI out of the box: is there something Harry can offer Voldemort such that Voldemort goes against his stated agenda

Precommitment / timeless decision theory: are there ways Harry can manipulate the unbreakable vow to force certain conditions in the future

Learning to lose: what if Harry surrenders and agrees to join Voldemort, with a commitment Voldemort finds convincing

Unintended consequences: Harry makes a convincing case that there is no way to outthink an inevitability other than to fulfill it in terms that are advantageous to you.

I really think didactic lessons about rationality are going to be better, and more appealing to EY's sensibilities, than trying to fanwank some way to use magic to kill 38 people in a single play. We just don't have the rulebook for that.

I made my suggestion.

Assuming you can take down the death eaters, I think the correct follow-up for despawning LV is... massed somnium.

We've seen somnium be effective at range in the past, taking down an actively dodging broomstick rider at range. We've seen the resonance hit LV harder than Harry, requiring tens of minutes to recover versus seconds.

LV is not wearing medieval armor to block the somnium. LV is way up high, too far away to have good accuracy with a hand gun.If LV dodges behind something, Harry has time to expecto patronum a message out.

... I think the main risk is LV apparating away, apparating back directly behind harry, and pulling the trigger.

Dear Eliezer,

For the best experience, if you have not already been following Internet conversations about recent chapters, I suggest not doing so, trying to complete this exam on your own. . . .

Although you've requested an individual exam format, two mathematicians aren't "the same smart" as the smartest of the two of them.

The Polymath Project got off to a slow start. . . Jozsef Solymosi from the University of British Columbia posted a comment. . . over the next 37 days, 27 people wrote 800 mathematical comments. . . Just 37 days after the project began Gowers announced that he was confident the polymaths had solved not just his original problem, but a harder problem that included the original as a special case. Link

You spend many chapters teaching Harry the importance of collaboration.

"Anyhow," Hermione said. "Captains Goldstein and Weasley, you're on duty for thinking up strategic ideas for our next battle. Captains Macmillan and Susan - sorry, I mean Macmillan and Bones - try to come up with some tactics we can use, also any training you think we should try. Oh, and congratulations on your marching song, Captain Goldstein, I think it was a big plus for esprit de corps."

So I'm afraid I urge everyone to do the opposite of what you've suggested and collaborate. Sorry.