The Girl Who Wrote on Water - The Royal Mages, #2

Sometimes a catastrophe isn't the worst of your problems As dust settles on the buried kingdom of Ymittos, Princess Derya faces a horrifying truth: her friend Princess Eliana has perished after failing to break an evil sorcerer's curse. Which means the next obstacle in the plot to enslave the continent is Derya's father - the Emperor of Cinar.  When the emperor tasks Derya with forming a crucial alliance, her only way forward is to race the sorcerer in a hunt for the magical scepter he lost a millennium ago.
If he retrieves it, he'll be unstoppable in his quest to dominate the world. Seeking the scepter in barbarian-controlled territory could cost Derya her life. But if she refuses the quest, she loses her right to the empire. And if she fails, there won't be an empire left to inherit.