Return Of The Runebound Professor summary:

Magus Vermil was a scumbag the most hated professor at a magic academy. Then someone murdered him. He never would have been heard from again if not for a lost soul from Earth by the name of Noah Vines. Transmigrated into Vermil's body, Noah assumes the man's runic powers and extensive list of enemies. There's just one problem. Noah has to teach class tomorrow, and he has no da** idea what magic is.