The Twice-Cursed Serpent by Scarlett D. Vine

Caes’s father was the prophesied hero who was supposed to save Ardinan from the Malithian Empire—but he failed. Reviled and used as a scapegoat for her kingdom’s anger, Caes is given to the enemies her father died fighting to destroy. While the Malithian emperor allows Caes to live at court, she is constantly guarded by Soul Carvers—undead magic wielders whose power stems from what killed them. Worse, Malithia’s crown princess believes Caes should be executed because the princess, thanks to a prophecy, sees her as a threat to her succession to the throne—and this princess has already murdered for less.