Shinobi!Seth

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.