Rarity is sent a scroll one day when she is busy working on a modern dress for one of her customers. The scroll had caught her by surprise, seeing as she almost never got any Canterlot Royal Mail. Upon opening the letter, she became petrified by what the scroll had read. Celestia had requested that she reform a dark hearted, impure, dark magic user that had been prevented from taking over the Crystal Empire only a year ago. King Sombra. Luckily for her, he appears to have an extremely bad case of amnesia.