Ulamog, the Ceaseless Hunger

Ulamog, the Ceaseless Hunger {10}

Legendary Creature - Eldrazi | Power/Toughness: 10 / 10
When you cast this spell, exile two target permanents.
Indestructible
Whenever Ulamog, the Ceaseless Hunger attacks, defending player exiles the top twenty cards of their library.