I'm not sure about the order of abilities here.

Yowie. That's... quite a mythic! :)

I wonder if it should have some kind of anti-reanimation clause. Perhaps even a subtle one like "When you cast ~, choose a player"?

How's this?

Yeah, that's the kind of thing I was thinking of.

It's still really good, even by the standards of 7 to 10 mana white "win the game" angels. I think those have been getting stronger, because they do have to come very close to "win the game" to be better than planeswalkers and titans.

But maybe it's still too good that in a duel this protects itself AND all other permanents AND you. AND all your creatures are unblockable. You're still vulnerable to a big enough Earthquake or Day of Judgement or Helix Pinnacle, but that's basically all.

I'm not sure what the right level is: 9-mana SHOULD be ridiculously good, but maybe it should be good, but auto-win only in a deck built around it?

Even Earthquake won't work: protection prevents damage from sources with the stated quality. Mutilate would still get round it though, as would Wraths of assorted forms (Final Judgment, Hallowed Burial, etc etc).

Um; will they though? I mean, it's the spell dealing the damage; not the player. Assuming that it works... yeah, this is pretty much a win button. About the only thing that can get around this is 'restart the game' and waiting for you to deck yourself (while somehow staying alive)

And, um, what happens if your opponent casts one too? It's the ultimate stall.

­True-Name Nemesis brought a new form of protection, and defined protection from a player to mean protection from all objects and sources that player controls.

Oh. That's confusingly different from other protection.