Tyranid Prime

Evolve is a triggered ability. “Evolve” means “Whenever a creature you control enters, if that creature’s power is greater than this creature’s power and/or that creature’s toughness is greater than this creature’s toughness, put a +1/+1 counter on this creature.”

A creature “evolves” when one or more +1/+1 counters are put on it as a result of its evolve ability resolving.

A creature can’t have a greater power or toughness than a noncreature permanent.

If a creature has multiple instances of evolve, each triggers separately.