Effluence Devourer is a mythic Creature — Crocodile card from Alchemy: New Capenna (YSNC), collector number 23.
Whenever you sacrifice Effluence Devourer or another creature, it perpetually gains "{2}, Exile this card from your graveyard: Create an X/X green Ooze creature token, where X is this card's power. Activate only as a sorcery." Blitz {B}{R}{G} (If you cast this spell for its blitz cost, it gains haste and "When this creature dies, draw a card." Sacrifice it at the beginning of the next end step.)