Steel-whip Assassin

Cowl {b}{b} (You may cast this spell face down
as a 2/2 creature for {3}. Whenever it attacks
and isn't blocked, you may turn it face up for
its cowl cost.)
When Steel-whip Assassin is turned face
up, the next time it deals combat damage
to a player this turn, target other player
loses that much life.