Dream Sovereign

For the duration, you have resistance to psychic damage, advantage on saves against fear, charm, sleep, and madness, and your Nightmare powers ignore psychic resistance. When a creature fails a save against one of your Nightmare powers, you may make it drowsy, frightened, or unable to take reactions 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.