ulamog the unending hunger

when this card enters the battlefield exile 2 permanents the opponent controls
indestructible
whenever this card attacks exile 5 non-land permanents target opponent controls if the opponent(s) can't do this exile the top 20 cards of there deck
put 2 cards the opponent has in exile into there graveyard summon 5 1/1 eldrazi scions with sacrifice this creature add {c} to your mana pool