Yummertog

Devour 2 (As this enters, you may sacrifice any number of creatures. This creature enters the battlefield with N times that many +1/+1 counters on it.)

Whenever a player casts a creature spell it gains Devour 2.

Whenever another creature enters the battlefield with a +1/+1 counter recieved from a Devour ability, put a +1/+1 counter on Yummertog.