A thousand years ago a power-hungry Centaur came to the land of Equestria with the intention to steal all the magic from her ponies and to use that power to rule it with an iron fist. Luckily the Princess's with the help of Scorpan and Starswirl the Bearded were able to defeat him and imprison him in the depths of Tartarus. Unfortunately for them that wasn't that last of him. Eventually after breaking free from his restraints and overpowering Cerberus he began to absorb magic from the other prisoners and beasts there. Even without their magic the beasts had great use to him and spent a century training them to be part of an army that he will use to take over Equestria and nothing can stop him. Or so he thinks! The Princess's have tasked the honorable Commander Branding Blade who was perhaps the greatest of all warriors in that era to go to Tartarus and defeated Tirek. They knew their was a good chance he may not come back alive but he accepted their task and went into the depths of Tartarus armed with the Sword of Harmony.