Exoth, Grand Exodus

Devoid, Deathtouch, Annihilator 6
As long as you control 8 or more white or black lands, all cards in your opponents graveyard are exiled. If more than 15 cards are exiled this way, you win the game. When Exoth, Grand Exodus enters the battlefield, if any opponent has less than half of their original life total, they lose the game.