Dark Dementing

A dark shadow creeps across the target’s mind and leaves a small bit of shadow essence behind, triggering a profound fear of the dark. A creature you designate within range must make a Charisma saving throw. If it fails, the target becomes frightened of you for the duration. A frightened creature can repeat the saving throw each time it takes damage, ending the effect on a success. While frightened in this way, the creature will not willingly enter or attack into a space that isn’t brightly lit. If it’s in dim light or darkness, the creature must either move toward bright light or create its own (by lighting a lantern, casting a light spell, or the like).