I Made Up Magic at Random, and Ended Up Teaching a World-Destroying Witch?

Joseph was transported to another world where magic had long fallen into decline, only to become the legendary Great Archmage. The bad news? He couldn’t use a single spell. All he wanted was to secure enough funding and make a clean escape before anyone discovered the truth. To avoid blowing his cover, he deliberately recruited only the “problem students” expelled by other academies. A princess with absolutely no affinity for magic. A blacksmith’s daughter with zero control over her power. Couldn’t learn magic? Clearly that was a talent issue—not his. So Joseph shamelessly borrowed magic systems from games in his previous life, making up spell slots, the Eight Schools of Magic, spell circles, and tier theories completely on the spot… To his utter shock, his students actually mastered them. Watching one of them calmly conjure a perfectly stable fireball in the palm of her hand, Joseph could only stare in disbelief. “I literally made all of that up… How did it actually work?!” At first, it seemed like fantastic news. That was, until he pocketed the academy’s funding and fled. “Professor… if you refuse to remain our teacher…” “…then this world has no reason to continue existing.”