Reckoning (The Tazavorn) by Sonya Weiss

The Great Extinction, the prophesied war between the humans and the Supernaturals, has begun.

Born a Supernatural, Juliet Sawyer has the ability to save the world from disaster. But after barely escaping the underground, power-sucking prison known as the Void, she finds herself on the brink of death and in the middle of a vengeful war. To survive, she’ll have to make a deal with her human captors. But the stakes are raised when she learns the government is holding her sister hostage. To rescue her, Juliet must become a weapon for humanity, fighting against her own kind—including Riley West, the boy she fell deeply in love with—and by whom she was abandoned.

Forced to desert Juliet, Riley is on a mission to capture the human’s president and bring her to the Supernatural’s king. But if he fails, there will be no stopping the Night of Grief, which will unleash horrors capable of destroying humans and Supernaturals alike. With battle lines drawn, amid a flurry of secrets and betrayals, can Juliet and Riley rescue their love as well as all life on Earth? Or will someone get caught in the crossfire?