The Obsidian Tower by Melissa Caruso
The mage-marked granddaughter of a ruler of Vaskandar, Ryx was destined for power and prestige at the top of Vaskandran society. But her magic is broken; all she can do is uncontrollably drain the life from everything she touches, and Vaskandar has no place for a mage with unusable powers.
Then, one night, two terrible accidents befall her: Ryx accidentally kills a visiting dignitary in self-defense, activating a mysterious magical artifact sealed in an ancient tower in the heart of her family’s castle.
Ryx flees, seeking a solution to her deadly magic. She falls in with a group of unlikely magical experts investigating the disturbance in Vaskandar—and Ryx realizes that her family is in danger and her domain is at stake. She and her new colleagues must return to the family stronghold to take control of the artifact that everyone wants to claim—before it destroys the world.
- Bisexual female protagonist (Ryx)