Book Shadow and Bone by Lee Bardugo

Surrounded by enemies, the once great land of Ravka is divided by the Shadow Canyon, a band of impenetrable darkness infested with monsters that lust after human flesh. And now the fate of the nation is in the hands of a lonely girl, Alina Starkova. Alina did not expect too much from life. Orphaned by a border war, she has only one person in her confidence - her best friend, Mal. When Mal is attacked by volcras, a magical power of such power awakens in the girl that it becomes clear: she is able to save the whole country. Alina is taken to the royal palace, where she will be trained as one of the Grisha - representatives of the elite society of magicians, led by the mysterious Darkling. She must face the secrets of the Grisha... and her own heart.