Daughter of the Drowned Empire by Frankie Diane Mallis

Cleopatra meets Throne of Glass in this stunning debut.

19-year-old mage Lady Lyriana Batavia is third in line to the Seat of Power in Bamaria: a position of wealth and privilege, but not safety. Bamaria falls under the rule of the Lumerian Empire, survivors of a celestial war whose island sank in the Drowning. Now all Lumerians submit to the Emperor and his strict laws about magic. He decides what magic can be practiced and what powers remain forbidden. He decides who will die for possession of forbidden magic.
Lyr’s own cousin was executed for wielding the wrong kind. And for years, Lyr has sworn to protect her older sisters, helping them conceal their own illicit magic.

But when Lyr must participate in the ceremony that reveals her power, she uncovers something else entirely. Something that means banishment from the Empire.

Faced with death in exile, and leaving her sisters behind, Lyr has no choice but to accept a deadly contract. She has seven months to train as a warrior and pass the Emperor’s brutal test of strength—all without magic.
But when she’s forced to train with Lord Rhyan Hart, the man she’s secretly loved since she was a girl—a feared warrior in exile himself, forbidden to her in every way—she’s in danger of losing far more than her family, life, and country.
Rebel forces, and an invading army, are destabilizing Bamaria, just as her family’s secrets threaten to reveal themselves.

Surviving the training, and saving her sisters may mean sacrificing her own heart.