Charzoid
I don't think it would be all to hard to make her horrifying in a realistic art style. Look at those creepy evil kids in movies that look cute but can both literally and figuratively slit a persons throat. Maybe have her writing on the skin of something she's kidnapped and looking into the foreground with an off-kilter smile that's almost to wide. Her eyes twitchy and rays of darkened rainbow light surrounding her. She made some pretty good creepy faces when she was bragging her plan of power to starlight.