Fiendish Familiar (5e Feat)
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Prerequisites: Intelligence, Wisdom, or Charisma of 13 or higher; The Fiend as your Otherworldly Patron; or a race with a fiendish ancestry
You form a contract with a fiend or devil, and through it gain an imp familiar. You can cast a special form of the find familiar spell. Instead of one of the normal familiars, yours is an imp, and the material components cost 50 gp instead of 10 gp.
Once you cast this form of the find familiar spell, you must complete a long rest before you can cast it again.
You are considered this imp's master. If you break the bounds of your contract (as decided by your GM) or otherwise lose the prerequisites of this feat, the imp will act in interest of self-preservation and flee to deliver news to Hell of your betrayal.