Trucela, the Blameshifter

As long as an opponent is controlling you,
Trucela, the Blameshifter has "If you would lose the
game, the player controlling you loses the game
instead. You gain life equal to that player's life total
and that player no longer controls you."

{t}: Choose an opponent. They control you until
the beginning of your next upkeep. Activate only as
a sorcery.

"It's all your fault."