Kellex, Monitor of Armies

When you cast Kellex, Monitor of Armies, creatures you control get +2/+1 until end of turn.
Annihilator 3 (Whenever this creature attacks, defending player sacrifices three permanents.)
Kellex has haste.
When Kellex is put into a graveyard from anywhere, its owner shuffles his or her graveyard into his or her library.