Eidolon, Waking Apocalypse

First Strike, Trample, Haste, Ward {4}
When Eidolon, Waking Apocalypse enters the battlefield, destroy target permanent.
Whenever Eidolon, Waking Apocalypse attacks,
exile the top X cards of your library, where X is
the number of attacking Dinosaurs you control.
You may cast a spell from among those exiled
cards this turn without paying its mana cost. At
the beginning of your end step, return all other
cards exiled this way to your hand.