Bogstalker Hydra

Bogstalker Hydra enters the battlefield with
X +1/+1 counters on it.
Whenever a creature you don't control dies,
put a +1/+1 counter on Bogstalker Hydra.
{1}{g}, remove a +1/+1 counter from Bogstalker Hydra: Bogstalker Hydra fights target creature.