Mud-Dwelling Hydra

Mud-Dwelling Hydra enters the battlefield with X +1/+1 counters on it.
Emerge (you may cost this card for {x}, if you do, it enters the battlefield with double what X was
+1/+1 counters on it and enters tapped and
attacking. Shuffle it into you deck at the end of
your end step) When Mud-Dwelling Hydra
destroys a creature, put X +1/+1 counters on it,
where X is that creatures toughness.
Travelers say sometimes pokes its head up for a quick snack