The Call of the Void By S. M. Gaither

War is building. Blood is spilling.
And the gods are not pleased.
Casia has survived her brother's attempts to crush her but the battle is just beginning. Bitter, wounded and carrying the curse of a dark upper-god, she journeys north to the elven court in search of allies.
The Court of Moreth holds knowledge, secrets - and power. The kind of power that could shift everything in her favour. But only if she can survive it.
Elander is losing his court, powers and divinity. But he's determined to stand behind Casia and bring his ancient, changeable allies to her side. He lost her once. He won't do it again.
His devotion to her may be what destroys him.
And when that destruction comes, it could change their entire world.