King of Darkness by Audrianna Hoover

Queen Arielle of Dagengrath rules from a throne that doesn’t feel much different from the locked tower room she left months ago. All she really wants is to be reunited with her loved ones in Luxerosi. But between navigating through a royal world dominated by power hungry men and trying to keep her vow to the Silver Queen, time is slipping away. As the risk of forfeiting her life looms again, two would-be suitors empower her to break apart the gilded cage around her.
A needless rescue attempt by Zacharias, James and Erickson leads them all on a journey into the Shadowlands. In the strange and forbidden land, Arielle’s abilities will strengthen and grow, prophecies will be fulfilled, and an intense love will take root. Arielle can only hope it will all be enough to defeat the cunning Haebor without sacrificing anything – or anyone – else.