Princess Celestia, feeling proud of her student (and her student's friends) decides to make all of them into Alicorns. To her, it seemed like a good idea at the time.

Now, as the Mane Six are trying out their new powers, she can only feel dread at the horror she has unleashed.

Cover Art credit to JamesHalt (his DeviantArt account) - I'm certainly not good enough to make anything like this!