Discord joins forces with Eggman to wreak havoc upon both Equestria and Mobius, and the heroes from both worlds have to work together to stop them.

Pinkie Pie's bright and friendly nature brings her to try and make quiet, scowling Shadow happy. But she has barely scraped the surface of Shadow's dark and tragic history.

The Mare-do-well incident brings Rainbow Dash to slowly tire beneath the treatment of her friends and begins to question her loyalty.