Thank you for pointing that out let me reconsider and revise..
I have a way of escaping that uses an item that has been established.
A: In the interest of keeping it simple the thing the most obvious answer for something Harry can do that he in theory could teach Voldermort/keep him talking is partial transfiguration.
B: Once Harry tells Voldermort that he can partially transfigure things, Voldermort will want to know the words/motions. Harry can say that he can teach Voldermort (he can't teach him how to cast a Patronus due to Voldermort's lack of love and he can't teach him how not to fear the death the way Harry does, but Harry CAN teach Voldermort how to see the world made up of component atoms given enough time) but it would be easier to teach while doing/give him a visible example of how it works as he teaches (not a lie, it would be possible to teach without doing, but Parseltongue allows for lies of omission) this can open the door to at the very least get the orders moved from “Kill him if he tries to cast a spell” to “lets see you do it while I stand behind/off to the side/under heavy shields” while Voldermort watches Harry try to partially transfigure something, or at least keep Voldermort listening longer than the first 60 seconds, and how he reacts to the knowledge will determine what options are open to us next.
C: Once Harry brings up the point he can also suggest to Voldermort that he might want to dismiss any of the Death Eaters who he does not want to have present while Harry explains/demonstrates the nature of this power. Because while he can speak only in Parseltongue, he'll still have to be showing it off in front of everyone Voldermort wants present. Voldermort is probably much too smart to actually fall for this, and lead to him dismissing any of the Death Eaters, but spelling it out can buy Harry a few more seconds/Voldermort might decide to dismiss one or two of his followers, there is no downside to doing it.
D: Harry explains in Parseltongue that he show the power of partial transfiguration by changing the glasses he is wearing, which he will take off, and hold in one hand, while he holds the wand in the other.
E: Harry will transfigure half of the glasses into half of a playing card.
F: As soon as the transfiguration is complete and around the same time Lord Voldermort possibly starting to recognizes the king of hearts, Harry will bite down on the card with his teeth, and pull with the hand that held it, ripping it in half.
Yes I know it was said that he was supposed to have a Toe-Ring as a Harry's "Emergency Portkey", but that's helpful the same way that the Chamber on the third floor was helpful at keeping people out. It's meant to look more helpful/threatening than it really is.
Given that Harry is wearing a ring just like that one, with Hermonine's body in it instead, where is Harry's "Emergency Portkey"? Well wouldn't the perfect place to have one, be something he'd never be without, something that he'd always have within hands reach, something he could finger and caress and adjust without drawing too much attention?
Say the glasses on his face...
G: As it has not been previously established within the story what Harry has done with the playing card deck he got from “Santa Claus” it is not impossible or against the rules to suggest that Harry transfigured the king of hearts into a pair of glasses. He is saving himself via efforts that he had taken in advance that do not directly contradict anything we have previously been shown (the equivalent of an extended flashback scene in Leverage which shows far more happen than the initial version of the scene we saw for the first time)
H: Likewise it has never been ruled that a portkey looses its powers if it is transfigured into some other form than the one it had in the first place.
I: It is reasonable to assume that with his life depending upon it, Harry can tear a card apart faster than the time it will take for Voldermort to realize what is happening, give the order to attack, or cast a spell himself (even non-verbally) and have the spell cross the distance between himself and Harry, likewise he can do it fast enough that he can at least avoid being fatally shot by Voldermort.
J: As they have walked several miles they are clearly outside the grounds of Hogwarts, so its wards are not in play. Given that the Death Eaters were able to apparate to the graveyard rather than flying there on broomsticks, it is safe to assume that the graveyard had not previously been warded to prevent people from apparating to or from it before they did.
There is nothing in the story describing Voldermort or any of the others warding it afterwards. The wards that Voldermort mentions are clearly of an anti-time turning verity since he mentions the six hour limit so they'd be anti-time turner, but clearly anti-time turning can't be the same thing as anti-aparating because you can Phoenix into Azkabhan but not time turner inside it, or apparate inside it.
Likewise it is unlikely that the place was set up previously before they arrived to let you have a one way apparation (in but not out, assuming such a thing is possible with apparation we see it requires a magical artifact or a phoenix to get into Azkhaban there may be no such thing as a one way apparation ward), because magic that powerful would end up getting noticed which is what Voldermort doesn't want to happen since he needed the site of his ritual to not stand out.
So we have not had it directly spelled out that apparition and by effect portkeys can't be used to leave the garveyard and we have some fair evidence that it could be possible With that in mind, tearing up the card should cause Harry to be taken “somewhere in London”, and the old saying “Anywhere is better than here” doubtlessly applies at the moment.
K: Not only will he be somewhere else, but unless Voldermort was lying in a situation he would have no reason to lie in, and possesses powers dealing with portkey location determination that haven't shown up anywhere else in the story (nobody in cannon Potter or this Potter is shown to be able to tell where a portkey will take someone just by studying it) it is logical to assume that if Harry tears the card up, then Voldermort can not simply apparate right after Harry, and instead will have to start searching London for him.
L: While Voldermort starts to look for him Harry can cast a Patronus to get help from others, and start using partial transfiguration to make whatever materials he expects to need.
At the very least, by this point he has surely avoided “immediate death”. While meeting the following rules.
Harry must succeed via his own efforts. The cavalry is not coming. Everyone who might want to help Harry thinks he is at a Quidditch game.
This solution requires no “cavalry” the outside help Harry has been given (the king of hearts) is already well established.
Harry may only use capabilities the story has already shown him to have; he cannot develop wordless wandless Legilimency in the next 60 seconds.
Harry's ability to partially transfigure objects is well established already within this story.
Voldemort is evil and cannot be persuaded to be good; the Dark Lord's utility function cannot be changed by talking to him.
This is not an issue as the solution involves Harry escaping from Voldermort, and doing so simply by obeying his orders until the very last moment.
Harry raises his wand or speaks in anything except Parseltongue, the Death Eaters will fire on him immediately.
Harry can partially transfigure his glasses back into half a playing card without raising his wand by taking off his glasses and holding them lower to the ground, it is not unreasonable for him to also say that this skill requires intense concentration in Parseltongue (because it does) which is why he will be slightly hunched over examining the glasses very carefully as he works on them. This will have the effect of getting Harry's teeth closer to the edge of the card so he can bite and tear more quickly.
If the simplest timeline is otherwise one where Harry dies -if Harry cannot reach his Time-Turner without Time-Turned help -then the Time-Turner will not come into play.
Though time travel could without question be useful in the immediate future (for a given definition of “future”) this plan does not require any monkeying about with timelines to work, Harry can have taken this precaution at any point in time since he showed Voldermort the card itself back in chapter 65.
It is impossible to tell lies in Parseltongue.
Everything Harry needs to say in Parseltongue is truthful.
1:Harry knows how to partially transfigure.
2:Harry could teach Voldermort how to do it.
3:Voldermort should send away any Death Eaters he does not wish to see the process being done slowly and carefully before their eyes as opposed to being used quickly in battle.
4: Harry will show off the skill by partially transfiguring his glasses which he will hold in one hand, while he holds his wand in the other.
Given that there is no rule 7: “Harry is not allowed to have taken any precautions we did not see him take on screen/in writing” this by following steps A through L Harry can arrive naked “somewhere in London” naked with half of his glasses and his wand, but alive.
Can anyone see a way to improve this plan/ any obvious flaw?
Okay the new plan works like this.
Harry will say in Parseltongue that he will transfigure two objects, one to show the basic principles, one to show the more advanced applications of it/what you can do after you master the skill. Either of the objects he will be transfiguring materials into will have any magical properties, they will not allow him to kill Voldermort, and they will not allow him to magically escape the graveyard.
Harry will then transfigure his glasses (using the hold in one hand method I described in the first plan), to change just the color of the lenses to black, without changing the color of the rims, legs or any other part.
He will confirm that this was transfiguration and not some other simple charm to Voldermort and ask if he is interested in learning more about this power.
Then he will need to transfigure a section of the ground into the most powerful and most harmless looking flashbang grenade.
At that point he simply needs to release his transfiguration in the right way (if he can control how something approaches the end point as he transfigures it, just reverse that skill and you can choose how it looks as his transfigured control of it fades away not a new power just a new use for an old one) so as to pull the pin on the grenade.
The change to his glasses will prevent Harry from being blinded though he will still be deafened.
This won't be too much of a problem though because we've already seen him command his pouch with hand signals.
With the Death Eaters unable to see him, and possibly having more difficulty casting spells as well (thanks to being unable to hear themselves talk meaning they may screw up the verbal components to their spells) and Voldermort likewise unable to see him and reduced to firing blindly.... Harry has a decent chance to making it to his pouch, if he has the magic to summon it to him so much the better, if not just run like f*.
Then he needs to tell the pouch to give the king of hearts, and tear it up while holding onto his pouch.
That is how he can escape.
Thoughts/reactions people?