Mage the Slayer
The player is a studying mage at a magical university. His mentor accidentally unleashed a powerful monster/demon that has destroyed most of the school and killed the master mages. The demon is hunting for any remaining mages at the school and will arrive at any moment. The only way to stop it is to find powerful spells in the mentor’s study. Unfortunately, the mentor was paranoid of his rivals stealing his work and hid all his best spells. Some of the best spells require using other spells to break barriers. Any use of magic within the study will attract the demon, lowering the amount of time to find spells.