Shosuro Assassin

Ninjutsu {u}{b} ({u}{b}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Shosuro Assassin deals combat damage to a player, that player gains control of Shosuro Assassin.
At the beginning of your end step, sacrifice another creature you control. If you can't, discard your hand.