Witch King’s Oath by A.J. Glasser

In a world of magic and politics, Prince Anryn of Ammar finds himself in the midst of a deadly conspiracy weeks before his wedding when royal assassins target him at a witch trial.
On the run, Anryn meets Maertyn Blackfire, an immortal witch cursed by the mages of Nynomath—Ammar’s enemy. Together, they uncover a curse on Anryn that hides a woman’s soul behind the facade of a man’s body, leaving Anryn questioning everything he knows about himself, including the question of who might want him dead.
Stuck waiting for her missing prince, Beatrice feels she can do nothing but dance the nights away and dream of the day when she will be Queen. Then maybe she can do away with the repressive laws of Ammar. But her ambitions and her heart are pulled in another direction when she meets Ciamon Caelt—a mysterious man with a shared interest in discovering Prince Anryn’s whereabouts.
When a brush with death awakens the witchcraft in Anryn’s true soul, the prince vows to challenge the king’s witch laws… by inviting a band of witches to attend as guests at the royal wedding!
With all eyes on Anryn and Beatrice, the two hope to flush out the assassins and end Ammar’s repressive rule—before Nynomath swallows the kingdom whole.