Sombra wasn't always a ruthless tyrant. There were many things that led to his desire for power that eventually corrupted him, turning him into the current megalomaniac he is. One of those things being a time where the ponies of the Crystal Empire were plagued by a strange malady that pervades across the entire empire. The cause unknown, and no cure that Princess Celestia or Luna could find could help Sombra's people recover from this strange illness.

It isn't until the current ruler of the Crystal Empire, Pristine Heart gives the young unicorn advice to broaden his research that the young unicorn discovers something that would not only save his people. But entirely change his life.