The MC started out as Peter Parker, a genius who was simply born with a weak physique, but when he gained super powers he became Flash Thompson instead of Spider-Man.
It started out as a slow and interesting story, with the MC being someone who tries hard but was unlucky and was born with various physical problems.
At first the MC was taking months to gradually discover his powers and it looked like it would be an interesting story about an MC who slowly learns magic and uses his intelligence to get the most out of it.
I expected him to slowly use magic, perhaps making potions, to cure his birth defects and slowly achieve the physique of a normal person and then become superhuman, while taking risks and using magic intelligently to fight stronger supernaturals beings.
Unfortunately around chapter 22 the story completely changed, it doesn't even feel like the same book anymore. The MC who still hasn't learned a single spell instantly becomes a super soldier and a Gary Stu, including instant popularity at school and joining a sport he didn't have any interest in before.
The MC changes from an interesting character to one of those generic football players you have in every teen series, he even starts to get revenge on the guy who bullied him once before, even though the MC has already taken his revenge and solved the problem a long time ago. Seriously, he got revenge and blackmailed the guy a long time ago, why is he doing it again after bemcoming a Gary Stu?