A Trial or Sorcerers by Elise Kova. I read it in one sitting.

Synopsis Ice is in her blood.Eighteen-year-old Waterrunner Eira Landan lives her life in the shadows — the shadow of her older brother, of her magic’s whispers, and of the person she accidentally killed. She’s the most unwanted apprentice in the Tower of Sorcerers until the day she decides to step out and compete for a […]