The user can force target to face their inner evil, either in a mental struggle or bring the victim's dark side into the world as a physical being. When a darkness is faced, it's arguably more powerful than the good half of the being. They're basically a physical manifestation of the being's past wrong doing, or current doing. They know the being like they know themselves, and that's a frightening thought. Victims are either corrupted, driven insane, or outright killed by the sensation of this ability.