Yuriko, the Tiger's Shadow

Commander ninjutsu{u}{b} ({u}{b}, Return an unblocked attacker you control to hand: Put this
card onto the battlefield from your hand or the command zone tapped and attacking.)
Whenever a Ninja you control deals combat
damage to a player, reveal the top card of your
library and put that card into your hand. Each
opponent loses life equal to that card's converted
mana cost.