The Shredder, Ninja Leader

Menace, First Strike, Bushido 2
When The Shredder, Ninja Leader leaves the battlefield, sacrifice a human ninja army
you control. If you do, create X 1/1 black human ninja creatures with skulk, where X is the sacrificed creature's toughness.
You fight well in the old style. But you've caused me enough trouble. Now you face: The Shredder.
— The Shredder