I Made up the Secret Method and Taught the World-Destroying Witch?

Linn traveled to a different world where magic was in decline, and became the dean of a mysterious academy in the North that was on the verge of bankruptcy. The bad news is that he doesn't know any magic. He just wants to defraud the royal family of some funds, and then run away with the money when the academy closes down. In order not to reveal his true identity, he specializes in recruiting "problem students" who have been dropped out of major prestigious schools—— A down-and-out noblewoman with zero elemental affinity, a blacksmith's daughter with zero control, a sickly abandoned baby with weak blood, a shadow branch expelled from the family... Can't learn? That is a question of qualifications and has nothing to do with me as the dean. Then he took out the settings from the game in his previous life and made it up with his eyes closed: Nine-ring magic system, spiritual sea meditation method, elemental resonance principle, explosive combat flow, dual-attribute fellow practitioner method... As a result... The students actually succeeded. Lin En was dumbfounded as he watched the students create a steady fireball from the palm of his hand and smashed half of the training ground to pieces. "I made it up, how did I get it right?!" This was originally a good thing, until the day he finished collecting the funds and prepared to run away—— The students blocked the entrance of the academy, and behind them stood the entire kingdom's mage group, the elf envoys, and the dwarf blacksmith master, all bowing: "I beg you, Dean, to stay. The Holy War on the mainland is about to begin. Please serve as the commander-in-chief of the coalition forces!" Lin En was numb. How could he become the recognized ancestor of all laws in the mainland when he was really just messing around with money?