Fate Breaker by Victoria Aveyard

A dark fate descends. A shattered alliance must rise.

The Companions are torn apart and the realm hangs in the balance, at the edge of ruin. Taristan and Queen Erida rise triumphant from the battlefield, while Corayne barely escapes with her life; her Companions left behind to uncertain fates.

But not all hope was lost: Corayne managed to steal Taristan's Spindleblade. Without it, Taristan can’t rip open any more Spindles. Without it, he can’t end the world.

Now, from every corner of the realm, the Companions race to reunite while they rally old allies and seek unexpected new ones, in one final push against darkness.

But Taristan and Erida are all but invincible. With their cruel god, What Waits, on their side, they will sacrifice anything and anyone to his hunger.

Everything has come to this. In the final clash between good and evil, a ragged alliance makes its bravest stand against a ruthless enemy . . . and the demon god who would consume the realm entire.