Archfiend's Mantle

Wear your patron’s authority as a mantle of horns, shadow, flame, chains, or wings. For the duration, you gain resistance to fire, necrotic, psychic, and force damage, and when a creature fails a save against your Pact power, you may charm or frighten it until the start of your next turn.

This power has its own stable page so it can be linked from any character, item, location, story post, bargain, curse, or future reward.