Fate Breaker (Realm Breaker #3) by Victoria Aveyard

Prepare for a larger-than-life, unforgettable finale to the instant New York Times bestselling Realm Breaker series, where a shattered alliance must rise from the ashes to make their final stand against a ruthless enemy…and the demon god who looks to shroud the entire world in darkness.

Change your fate—or kneel to it. The Companions are scattered and hopeless, torn from each other. After Corayne barely escapes with her life, she must forge on alone, leaving her blade broken and her allies behind her. Her only consolation—Corayne now has Taristan's sword, the only Spindleblade left in existence. Without it, he can’t rip open any more Spindles. Without it, he can’t end the world. But Taristan and Queen Erida will not be defeated so easily.

Both will burn the world to bring down Corayne—and bring forth their demon god, What Waits, ready to claim the realm of Allward for his own. In a final clash between kingdoms and gods, all must rise to fight—or be destroyed. Everything has come to this.