Revan, the Ryukaze

Ninjutsu {1}{u}{u} ({1}{u}{u}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Revan, the Ryukaze deals combat
damage to a player, they reveal the top card of
their library. You may play that card without
paying its mana cost. If you don't, exile it.
Whenever an opponent casts an instant or sorcery spell, return Revan to its owner's hand.