Mayhem and the Mortal - Shanora Williams

One mission. One curse. No escape. Zaira doesn’t want a hero. She needs a weapon. To save her sister from a soul-devouring curse, she has to cross The Shallows ― a nightmare landscape of ruined magic, shifting paths, and vicious creatures that eat people alive. Her guide ― Thane Valkor: sorcerer, assassin, walking red flag. His name clears rooms. His magic kills quietly. And whatever he’s really after, it’s not salvation. He promises to help. He might even mean it. But Zaira knows better than to trust a liar with a blade and ice in his veins. She just doesn’t have a choice.