Archmare

For the duration, you become a living nightmare. You are immune to being frightened, charmed, put to sleep, or affected by madness against your will. Your Nightmare powers ignore psychic resistance, and once per turn when a creature fails a save against one of your Nightmare powers, you may also make it unconscious, frightened, or confused 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.