The Most Powerful Archmage To Have Ever Lived [OPMC / Hidden Genius / Regression / Magic Academy / Academy Building]

He cultivated his mana core for a thousand years alone on an island. The last thing he remembered was looking up at the sky and seeing a bright light. Then he woke up on the side of a road in the body of a five-year-old child. A court mage finds a confused child abandoned on the side of the road and takes him in, raising him alongside his own daughter.  Now Ren's trying to piece together his past while navigating academy life, awkwardly making friends, and attempting to hide his power. But Demons that vanished a millennium ago are returning, and now Mages are disappearing. Where once the kingdom had thousands of practitioners—now there are barely hundreds left, and their numbers are rapidly declining. Ren may be the only thing standing between the extinction of mages, or their salvation. And from the ashes, Ren will have to build something new.  - Updates M, W, Th, F (4X/Week)  - 2500 - 3500 word chapters - OP MC - Regression/Hidden Genius  - Academy Building (Later arcs)  -  Heavily inspired DnD magic systems and spells