Thousand-Faced Shadow

Ninjutsu already asks you to swing with something unblocked, then swap it out for a ninja at the point of no blocks. Here that swap does double duty: bouncing one attacker to hand replaces it with a flyer that clones a second attacking creature, tapped and attacking, so a board that got through unblocked trades one attacker for a fresh copy of your best swinger. The copy targets another attacking creature, meaning the fodder is whatever you already committed to the red zone, and the reward scales with how threatening that attacker is: clone a bomb and you have two of it in combat this turn. The gating clause is the entry condition. The trigger fires when this enters from your hand while attacking, so ninjutsu is the natural delivery, but any effect that puts it directly into the red zone from hand satisfies it too. It offers nothing on a turn without a combat step already underway: no defensive block, no flicker value, no clone off a stalled board. The payoff exists only inside a combat the attacker is already committed to. Outside that window it is a one-mana 1/1 flyer with a ninjutsu cost you may never pay. That narrowness is the design: a combat-step multiplier wearing the frame of an evasive one-drop, cashing out only when the game is already a race and the red zone is full.