She USED to be an alicorn. Then most of her horn broke off and weakened her magic to the point where very simple spells are extremely difficult for her to preform. She became twisted, depressed, and insane from the jarring damage to her skull and horn and for a time almost successfully destroyed ponyville and k!lled Celestia, but she suddenly became confused and traumatized and fled. Her life is now in Cloudsdale at the Rainbow Factory. She never uses magic anymore and she is somewhat sane now.