The Runesmith - Chapter 486: Rude Awakening.

Three years after graduating from Hogwarts, Felix entered the school again, only this time as a professor!

What kind of sparks will come from the combination of Muggle wisdom and magic?

In a world dotted with World Entrances to a demon world, demons have invaded humans for centuries. Humanity has united and one of the most ancient sects in the world, the Archean Mountain Sect, has set up an entire education system in the form of Dao Academies and defenses at the World Entrances.

Some say reincarnation is a blessing, but for me, it's a dreadful curse. Cursed with endless reincarnation, I've been reborn as a villain 137 times. And all 137 times, I've been toyed with and killed by heroes who are far more cruel than the said villains... If I can't win no matter what I do, then I'll crush those so-called heroes at their very roots. - Quality Fan Translations, Made by Fans for the Fans - Villain Takes Over The Academy

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.