When Luna became Nightmare Moon there was a battle between the two great goddesses. Celestia was defeated by the overwhelming power of Nightmare Moon. There was Celestia at the mercy of her corrupted sister but Nightmare Moon was to far gone. In an effort to extinguish the light, she threw Celestia into the deepest dungeon she could find. Lost to the light, the land of Equstria began to fall away.
Two hundred years pass, leaving the Princess of Light to her own thoughts but a prophecy had been foretold two ages ago that could save the world from Nightmare Moon. When all would be lost there would be a hero that would rise up from the ashes of defeat and restore balance to the land of Equstria. He would face many trials and his path would be littered with the pains of his heart.
Celestia doing everything within her power contacts an angel by the name Icerus to seek out the one that the prophecy told of.