Yujin, Shi Director

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 mana value.

"I pledge to change the system with my hands… No matter what."