Est, Titan of the Depths

Annihilator 3, unblockable
When Est, Titan of the Depths enters the battlefield,
exile the top five cards of an opponents library. Those
cards remain exiled as long as Est, Titan of the Depths
is on the battlefield. You may cast those cards and you
may spend mana as though it was the color to cast
them.
When Est, Titan of the Depths leaves the battlefield,
return the exiled cards to their owners hands.