Adaptive Predator

Evolve (Whenever a creature enters the battlefield under your control, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Ferocious - {t}: Adaptive Predator fights target creature you don't control. Activate this ability only if you control a creature with power 4 or greater. (Each deals damage equal to its power to the other.)