Minor Works of Meda by Juliette Caruso

She’d be the most gifted witch in centuries, if she had an ounce of power in her veins.

With weak magic and no social graces, Meda’s dreams of becoming a great witch are impossible. It doesn’t matter how much harder she works than her rival, Kalcedon: the heartless half-fae has so much magic that just being near him makes her blood sing.
When an ancient Ward-spell falters, a wave of devastation crashes across their islands. If the spell fails for good, they’ll be at the mercy of the cruelest fae lord their world has ever seen. But if Meda can translate the ancient spell fast enough to understand who is destroying it, and how, she won’t just save the isles. She’ll finally prove her worth.
Meda’s sharp mind isn’t enough to win against an unknown enemy. She’ll also need Kalcedon’s endless well of power. As they travel the Protectorate’s islands, navigating grief and racing against time, she begins to see a new side to the half-fae. Behind his cruel words, there may be a battered heart more human than Meda dares admit… and a man who will do anything to keep her safe.

…Even if it costs the whole world.