Ashes of the Wind by Madalyn Rae

Thrown into a world of fire, all Adria Kane has left of herself is her humanity. After killing Brigit, one of the four First Elementals and the original goddess of fire, Adria is forced to assume her role in the world of Elementals. Now Brigit’s daughter, Astrid, wants her dead and is the only person on earth capable of completing the task.
When word comes that Astrid has a hoard of lessers ready to fight to the death, Adria is forced to make a decision that could risk the lives of not only the ones she loves but the lives of those of her elements.
Secrets are revealed and lives are lost as the elements of water, fire, earth, and air join to protect their gods.