1000 years ago...
When King Sombra was sealed in his icy prison by the rulers of Equestria, a chip of his horn was cut off leaving his dark magic behind. The magic manifested, and roamed the land until it found a suitable host, That host was Azure Shine, but instead of taking over, Azure Shine gets pregnant.

Now Azure Shine has a foal out of no where, that possibly could be a copy of King Sombra, but that foals name is Grey Star.