Starlight Glimmer has passed several of her friendship lessons with flying colors, but the Princesses (besides Twilight) and Shining Armor have disappeared and Discord has gone rogue despite his reformation! What's worse is that a new and even bigger threat than Tirek and Sombra combined is out to destroy Twilight and her friends! Can Twilight and her pupil, Starlight take on this astonishingly evil being?