Mikasa, the Pure Blade

Ninjutsu {1}{u}{b} ({1}{u}{b}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking. )
All Ninja creatures have frenzy X, where X is the number of unblocked creatures you control.
(Whenever a Ninja attacks and isn't blocked, it gets +X/+0 until end of turn. )
Strike Quickly. Strike Silently. Strike with final resolve.