Planet of the Magi by Erin Lale
This newly-released fantasy got left off of yesterday's Booknado post. Here's the blurb for Planet of the Magi by Erin Lale:
Dije is expected to become a Magus, a wielder of dark magic, but she wants to learn the forbidden white magic. To pursue her dream, she must leave Magi-ta and go to a school run by the people who betrayed and marooned her ancestors after the end of the Rimmy War. Dije has to become a mercenary just to get off the planet, but, influenced by the pacifist pagan Fruitioners, she constantly questions the morality of a warrior path. Then she finds out the deadline is looming for the prophesied return of the alien destroyers that the original Magi were engineered to fight. The world she rejected needs her to save it. Can her magic stop an alien invasion? Will she choose the way of war?
Planet of the Magi is available on Smashwords.