The Mages of Starsea by Kyle West

Lucian dreams of a new life outside the cesspool of Earth. Unfortunately, his wish comes true when the government identifies him as a mage.

This revelation comes with a horrible cost, though. Mages are plagued by a wasting disease known as the fraying, which eventually leads to death.

Knowing he doesn’t have long to live, Lucian abandons everything to travel to a distant planet in order to find a cure. He soon discovers that the fate of the galaxy rests on his shoulders…and must overcome all odds in order to save it.