Twilight Sparkle has always been Celestia's most faithful student. Her magical skills are at the top of the ranks, and she is such a great and caring friend. But one day, as Twilight studies a mysterious dark book, she will learn a spell that will transform her into a great, and powerful alicorn. Twilight sees that the spell is more than just difficult, but she tries it for practice. When Twilight's magic prevails, and she becomes a lean alicorn, she is overcome with joy that her magic has increased. But what will happen when Twilight becomes overcome with a surge of evil, dark magic that takes over her very soul?
It's up to the rest of the mane six to stop the new, powerful, and evil Twilight. Can they save their dear friend from the dark arts?

This story includes obvious hints to FlutterDash, Rarijack, and Twinkie Pie!