Dragon Soul by L.J. Swallow — book slip

Calla, a girl with forbidden shadow magic, is a threat to the kingdom. When her powers are discovered, she faces a death sentence, but three powerful men from the royal court intervene.

Leander, Rohan, and Galen, each with their own strengths and secrets, are tasked with recruiting magic users to fight against the Ebon Queen's dark forces. They never expected to find a daughter of shadow.

As Calla journeys with them, she discovers her power is more dangerous than she realized, and so is the bond forming between them. Together, they must navigate political intrigue and enemy territories to save their realm.

First in the 'Daughter of Shadow' series.