The Season of Flame (Patreon)

Experimental Blood-fueled Hellfire Pyromancies are the name of the game with these cults and subclass; they've got the power and flexibility to go a whole cultin' career without ever casting a non-fire spell, though said career is likely to end with them consumed by their own magical recklessness.

Cults of the Hellfire Master

Warlock Patron - The Hellfire Master

Mephistopheles