Ulamog, the Infinite Gyre

When you cast Ulamog, the Infinite Gyre,
destroy target permanent,
Annihilator 4 (Whenever this creature attacks,
defending player sacrifices four permanents.)
Ulamog is indestructible,
When Ulamog is put into a graveyard from
anywhere, its owner shuffles his or her
graveyard into his or her library