Cave Hydra

Morph {4}{r}{g} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Cave Hydra enters the battlefield or is turned face up, you may pay X. If you do, put X +1/+1 counters on it. If Cave Hydra was turned face up, you may have it fight target creature.