Thromok the Insatiable is a mythic Legendary Creature — Hellion card from Planechase Anthology (PCA), collector number 106. Current market price: $2.93, TCGplayer market prices via Scryfall.
Devour X, where X is the number of creatures devoured this way (As this creature enters, you may sacrifice any number of creatures. It enters with X +1/+1 counters on it for each of those creatures.)