A tattoo in the shape of a bell, dented as though chewed on by the jaws of a large dog.

Demonic Inheritance. You learn the Abyssal language and have immunity against the Frightened condition.

Mark of the Beast. Once per day, you may spend one spellslot of any level to summon your Abyssal Hound of Ill Omen instead of spending sorcery points.

Abyssal Transmutation. Whenever a spell you cast would deal fire damage, you may spend 1 sorcery point to change it to necrotic damage instead.

Call the Void. Once per day, as a ritual, you may cast the spell Commune, reaching out to the Abyss. You cannot be sure who or what will answer your call. When the spell ends, make a DC 15 Charisma check. On a success, you receive a demonic boon. Roll a d20 and tell the DM the result.