HOLY CRAP THIS IS SWEET. Reminds me of my own unicorn character, Mourning Star. He's actually just my other unicorn character, Skill Set, when he over-depresses himself into something of a nearly-blind rage (I say nearly-blind because he's still aware of what he does, but he's just as deadly as if he wasn't). He's normally white with golden blond hair, but when he becomes Mourning Star, he turns so black that sometimes he looks more like a void than a solid object, like something is missing rather than there, his eyes begin to glow white with energy, and his magic becomes almost entirely dark-based. The reason behind the name is a reference to Satan (no, I do not worship Satan). Supposedly, Satan's original name, Lucifer, means "Morning Star". When Skill Set becomes Mourning Star, he is so powerful, and his presence is so depressing and emotionally effective that some would think he was possessed by the devil, but instead of having pure hatred, his power spawns from hatred and extreme sorrow for the good things that were prevented by various negative occurrences, recent or otherwise, hence the name Mourning Star. Plus, his battle cry sounds more like that of a tortured young soul, which is part of why his very presence is so emotionally powerful in the first place, so that's also part of where the whole "mourning" thing comes from.