Well, seems like we passed.

Right, so what he actually must asked them for is a gun that was already banned in the UK but not in the U.S.. Maybe one of those ‘assault rifles’?

1) Cancel the Transfiguration on his father's rock, use it as a physical shield to block Death Eater attacks.

It is lying in a pile on the ground. How will he use it as a shield?

Here is my best attempt at a delaying tactic, after sleeping on it. Please tear apart/suggest better ways in which LV might tear apart, to replace the poor placeholder responses he has here.

--

"Agree that I musst die, if it ssavess world. But thiss iss not besst way to kill me. Ssee how you can benefit more, given your goalss."

"Explain."

"Believe power you know not doess refer to power to desstroy life-eaterss. Life-eaterss will find you eventually, teacher. Know you. Will hunt you down, ssomeday. Eat all of you, all of world and magic, in the end."

"Sso you will give that magic to me, now."

"You can never reach needed sstate of mind - incompatible with deadly indifference. Sschoolmasster could never casst - incompatible with acceptance of death. Majority cannot casst, and in the tessting, sstandard defence againsst life-eaterss iss ssacrificed. Will weaken your alliess greatly, should I randomly try to teach."

"What do you proposse, then?"

"Take me to life-eater prisson. Allow me to pour out my life and magic there, eradicate them wholly. How I wisshed to do sso, during the resscue! You called me back, then."

"..."

"Many advantagess to you in thiss. Can decimate your final enemy, wipe out their greatesst colony, certainly buy you yearss. Removess them before Wizengamot'ss death throess can releasse them againsst you. Freess your remaining alliess, ass thosse here failed to do. And I am utterly desstroyed - can leave no ghosst behind me. Nothing to fuel ssecret devices of Sschoolmasster's. Presumably, reduced rissk that your great creation will recognisse my spirit - for I doubt you have tessted that."

"You will not desstroy all of them, and sso I will have to find another ssolution anyway."

"Ssolution iss girl-child. Sshe iss closse to learning sspell, and now immortal. My death could drive her to hunt life-eaterss forever; thiss iss not beyond your sskillss at manipulation. You know sshe wantss to be a hero."

How about simply telling Voldemort that he doesn't have a complete model of time, and give him a bunch of examples of things until one is found which voldy wouldn't have predicted. Suggest to voldemort that he should keep harry in a coma until he has done more experiments with Time to derive its nature, and then kill Harry without waking him up.

I was going to correct you

Some of these items are expensive even in the Muggle world, and your contact may have to go outside Britain; but one hundred Galleons will be enough to pay for it all

But then I remembered -- no handguns in Britain! That was a clue I missed right there!

Could he tell Voldemort aout partial transfiguration and request his own life spared?

What's the difference between an orthodox Discordian and a heretical one?

1) Cancel the Transfiguration on his father's rock, use it as a physical shield to block Death Eater attacks.

2) Patronus 2.0 to block Voldemort's attacks - we only know for a fact that it blocks Avada Kedavra, but it is an instance of Harry's magic, which seems to interact poorly with any of Voldemort's magic. If he's got sufficient control, put the Patronus coincident with Voldemort's body - at minimum it'll prevent him from doing too much with magic, and with luck it'll actuaolly cause some sort of resonance that disables Voldemort.

Those two together buy him a few seconds, but no more. After that, frankly, I'm not sure - my best guess is that he'll Accio his pouch and pull out some kind of Muggle gadget, but we already know Voldemort can trump that by ripping the items away. (Unless one of them's a hand grenade, and Voldy doesn't notice? Unlikely...). If he can hold the items long enough to Time-Turn, he can summon some help, presumably pre-mirror Dumbledore. That said, I'm not sure how much that will help.

For a rather out-there option, he is Tom Riddle, and has some of Voldemort's memories. Can the Death Eaters be convinced to change teams? Unlikely, but not specifically prohibited.

If your prediction is lower than 50%, what you're really saying is, "Of all the hypotheses I that have been elevated to my attention, this one is most likely; however, I am so uncertain that I am more likely to be wrong than right."

Or in other words, to paraphrase Eliezer, I'm fairly sure that random person's name isn't Klein, but I'm very sure it's not Ktlzybplq.