Nightmare Academy: Monster War (Nightmare Academy #3) by Dean Lorey

WITH THE FIFTH SUMMONED, THE MONSTERS OF THE NETHER HAVE BEEN UNLEASHED.

Now the only person who can prevent all-out armaggeddon is Charlie Benjamin, and the only weapon capable of defeating the Fifth is the Sword of Sacrifice.

There are only two problems:

Charlie Benjamin is in exile.

And no one has ever managed to get hold of the Sword of Sacrifice...