Biomancer's Familiar

Evolve (Whenever a creature enters the battlefield, if that creature has a higher power or toughness than this creature, put a +1/+1 counter on this creature.)
If Biomancer's Familiar has five or +1/+1 counters on it, it gains trample, flying, and menace.
{2}{g}{u}{t}: Regenerate another target creature, then put a +1/+1 on it.