Mel, Defender of Neverland

Flash, Flying, First strike, Deathtouch
When Mel, Defender of Neverland enters the battlefield create {x} 0/3 Black unicorns
Unicorns you control gain +X/0 where X is the number of unicorns you control.
{w/b}{r/w}{t}, sacrifice a creature: create X 0/3 unicorns where X was the sacrificed toughness