Pinkie Pie's 'cousin Horsey' comes to visit, but Twilight Sparkle is suspicious. Sometimes we wear masks to hide our true feelings... sometimes that can be taken literally.
History states that Princess Celestia banished Nightmare Moon away to the moon with the Elements of Harmony, that's true. But there was one other being present at the time who aided Celestia. A being who's magic can only be used by him and
Twilight Sparkle has finally perfected a device allowing ponies to speak to each other over great distances. Unfortunately, the first call she receives is from Pinkie.
After a teleportation spell goes wrong, Vaati finds himself in Equestria. The world's most powerful mage is about to learn about the world's most powerful magic: Friendship.