A game is being played. A dreadful, chaotic foe decided to leave a lasting impression. Now, anything with the power or ability to bridge dimensions is dropping a champion in or around Equestria. In the incomprehensible mess of rules enforced, the first is the clearest - the champion had to once be human.

Of course, even the best laid plans fail. When you rip open pathways between dimensions, stuff you didn't want is going to fall through.