Yerok was once a feared demon of Hell's army. He was respected and revered for his ruthless efficiency on the battlefield. The demon fought for Hell, against the impossibly powerful armies of both Heaven and Earth, and always came out on top. Nothing could stop him... until the day he broke an ancient law of Hell.

Yerok was sealed away for his crime. Forced into a solitary prison in an unknown realm, he stayed there until his mind shattered, and continued to suffer alone. Then, one fateful day, two ponies stumbled upon his tomb. They mined through the wall of his prison and awoke him from his sightless, soundless abyss. Now, the lands of Equestria are at the mercy of one of Hell's greatest warriors... may God have mercy on their souls.