Djo'ssin of the Shadows

Ninjitsu {4}{b} ({4}{b}, Return an unblocked
attacker you control to hand: Put this card
onto the battlefield from your hand
tapped and attacking)
Whenever Djo'ssin of the Shadows deals
combat damage to a player, exile the top
card of each player's library. You may cast
one of the exiled cards this turn, it's mana
cost is reduced by {2}. Then, return that
card to the exile where it originally was.