Nine Lives
Oracle Text
Hexproof
If a source would deal damage to you, prevent that damage and put an incarnation counter on Nine Lives.
When there are nine incarnation counters on Nine Lives, exile it.
When Nine Lives leaves the battlefield, you lose the game.
Preventing 9 sources of damage is pretty good, especially against decks that plan to win with a small number of large creatures. Stalling such a deck for 4-5 extra turns is quite powerful. Against Cavalcade decks, it pretty much reads "gain 9 life" which isn't as good. This will probably be better in Standard than in Historic where things like Cleansing Nova will instantly kill you.