Sylvia, All Life's Guardian

If a source you control would deal damage to a
player, that player gains that much life instead.
At the beginning of your end step, if each
player's life total is greater than or equal to twice
their starting life total, you win the game.
{3}: The next time target creature or planeswalker
would be destroyed this turn, exile it instead,
then return it to the battlefield under its
owner's control.