Episode List: http://mlp.draconequus.com
Princess Celestia gives Twilight Sparkle Star-Swirl the Bearded's notebook with a final, unfinished spell that she thinks Twilight can complete. When Twilight evokes it, it causes her friends - through the Elements of Harmony - to have their cutie marks and respective destinies switched, resulting in disasters around Ponyville. Twilight finds a means to convince each of her friends of their proper place with the aid of the Elements, restoring her friends to normal, and is able to complete Star-Swirl's spell, accounting for her friendships. When she does so, Twilight is magicked by the Elements to an ethereal place, where Princess Celestia congratulates her on her completing her journey, and helps her transform into an alicorn (a winged unicorn) and crowns her as a new princess. Twilight's ascension is celebrated by her friends and across Equestria.