Reign of Magic by K. M. Shea

Angelique’s spirit is almost broken.
She has sacrificed, she has trained, and she has driven herself to exhaustion while battling her way across the continent. But all her efforts have led to nothing. She still hasn’t uncovered Evariste’s location, or the identity of his captors.
Yet the occurrences of evil magic across the continent show no sign of slowing. Wyverns, goblins, trolls, and other evil creatures have become almost commonplace. And the attacks on the royal families and her fellow mages have continued to escalate.
When Angelique is ambushed by one of those who kidnapped Evariste, she is forced to face the truth: her core magic—which she despises—may be the only thing standing between her world and the coming darkness.
For those who have captured Evariste aren’t finished.
And their plans are far older and more devastating than anyone could have guessed.