Ulamog, Bearer of Pain

Devoid, indestructible
When Ulamog, Bearer of Pain enters the battlefield, sacrifice it unless you sacrifice 4 other Eldrazi creatures.
Whenever Ulamog, Bearer of Pain attacks, you
may put 5 cards your opponents own from exile
into their owners' graveyards. If you do, you may
cast an Eldrazi spell from your graveyard
without paying its mana cost.