Release the Deathspores

Destroy target nonblack, nongreen creature.
Mold 1 (Put a spore counter on target creature. That creature has "When this creature dies, create X 1/1 green and black Fungus creature tokens, where X is the number of spore counters on it." For as long as it has a spore counter on it.)
Some fungi can choose between to types of spores to produce. Those meant to mature and reproduce. And, for defense, those meant to kill.