The stakes have never been higher than in the final installment of Magisterium from the bestselling powerhouses of Holly Black and Cassandra Clare.Callum Hunt has been a hero and an outcast, a force of good and a portent of evil. While the doors of the Magisterium have been open to him, he has never felt entirely welcome. If anything, he has felt others' resentment . . . and fear.Now, as he begins his final year at the magical school, his place is less certain than ever. With one unique exception, he is estranged from most of his friends. A furtive darkness still hounds him. And the greatest challenge he will ever face is right around the corner.In this monumental conclusion to the Magisterium series, bestselling authors Holly Black and Cassandra Clare push Callum to the brink of annihilation, showing how magic has the ability to both save and doom, create and destroy.