My Best Friend is an Eldritch Horror (light novel) vol. 2

Damien is feeling the pressure. His first year at Blackmist Mage College is coming to a close, culminating in a no-holds-barred tournament that will push his nascent magic skills to the limit. His overachieving friend and roommate is keeping a secret that could kill her, and his unhinged professor's lessons might end up putting them both in worse danger.

In the meantime, Damien continues to hide the existence of Henry, his Eldritch Void Companion. Things were frightening enough with Henry's plan to destroy the mortal plane, but now the mismatched pair realizes there's an even greater threat to contend with... And both of them are the target!