Loki, God of Mischief

+2: Shuffle 4 cards from your graveyard into your library, then put another card from your graveyard on top of your library
+2: All creatures you don't control gain -5/-5 until end of turn, you gain 3 life for each creature affected this way.
-10: All creatures you control gain undying, reach, double strike, and vigilance. If any creatures are destroyed this turn, you win the game