After Tirek is locked away for good, all was fine, until someone appears to explain the true origin of him and his brother. Dead set on tearing down Equestria and making the world his, he allies with mysterious forces that turn the prison of Tartarus into his personal paradise. Desperate, Twilight and friends summon the first human ever, or at least who they think is a human. He's wearing a helmet and armor, so they can't tell. Yeah, it's Doomguy, and he's going to Tartarus this time.