A mysterious fairground appears on the edge of Ponyville one day without any explanation. What magic lies within and will the citizens be ready for it.
On Princess Luna's first Nightmares Night she wanted it to last longer. But when she casted her spell it instead grew out of control and transformed Ponyville into a Town for Nightmare Night.
Almost every pony in Equestria has been turned into cows without any explanation. While Princess Celestia and Luna deal with the crises, Rarity, Applejack, and Fluttershy venture into the unknown looking for Zecora to help solve their ailment
The day Twilight earns her cutie mark, something unexpected happens that no pony saw coming. Twilight undergoes a transformation due to an absurd amount of magic and literally becomes the spirit of magic.
New spells are fun, and Twilight loves practicing them. An ill-timed sneeze has made her latest spell go a bit out of control, though, and now she's stuck as a tiny kitten, trying to deal with a pony-sized world.
After a minor disagreement with her sister, Luna decides to seek a little freedom from her presence. A chance encounter with a griffon gives her an interesting method.
After Diamond Tiara confronts her mother in the episode "Crusaders of the Lost Mark," she is gifted a set of wings and a horn. But her mother forces her to go to Boarding School, where she learns to face herself and find out who she wants to be.