Betrayed? My Pet Devours ALL!

Betrayed and stripped of his supreme bone, a fallen genius is thrown into a deadly abyss! Near death, he forms a blood pact with a dying black beast. Surprise! The "useless" pet is a mythical devourer! Feasting on monsters and enemies, they level up insanely. Now, he returns to crush the traitors and bathe his hypocritical sect in blood!