Avacyn, Angel of Hope

Indestructibility is the one keyword that turns a board state into a fortress, and granting it to your entire team at once is among the most lopsided things a single permanent can do. Wraths stop working. Targeted removal whiffs. Combat math collapses, because your blockers survive lethal damage and theirs do not. The catch is that the protection is anchored to the one permanent that does not protect itself from everything: the angel grants indestructibility, but cannot grant itself anything it does not already have, so the answer is to ignore the board entirely and remove her instead. Exile effects, bounce, sacrifice edicts, and minus-toughness all route around the keyword and take the linchpin with it. That is the tension the eight-mana cost is paying for: a body that, the moment it resolves, makes the other permanents you control functionally permanent, balanced against the fact that the whole structure leans on a single legendary creature an opponent now has every incentive to kill in the most oblique way possible. The flying, vigilance, and 8/8 frame matter less than what she does to the rest of the table; this is a card built to make a stalled board unbreakable and then end the game before anyone finds the exile spell.