The Chest has opened. Isaac is free. So is everything else once trapped within.

Discord tells Twilight how he became the Lord of Chaos.

Even the strength of a Mortal's Monado can't erase two god's power completely. Only banish it.

Twilight summons a human. It's on fire and smells of rotting fish. What went wrong?

A technically 'insane' human is dropped in Equestria by a misfired teleportation, crossed by the stars. Of course, this first thing he does in agitate the ponies in various rude ways. Both intentionally and unintentionally.