Tales of the Endless Empire - Chapter 125: So, who is stronger now?

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

In novels with a stud there is always a Senior Martial Brother like this:

In the early stages of the novel, his innate talent is high, his cultivation is good, his appearance is handsome, and he has an intelligent, cute younger Martial Sister as a fiancée.

In the middle stages of the novel, he is caught unprepared and defeated by a young disciple (the protagonist) in the sect who’s hardly remarkable at all. From then on, he falls from his godly altar and loses his brilliance. Even his young Martial Sister leaves him for someone else.

In the late stages of the novel, he continues to turn dark, going down the Demonic Path and becoming the major villainous boss. However, the protagonist still ruthlessly defeats him and his soul is eternally sealed.

Once Qin Mo opened his eyes, he discovered that he had become this Senior Martial Brother.

- Description from Novelupdates

“Kill Hamyuts Meseta”

A story about a world where all dead people become “Books” and are housed in a Library. The boy named Colio Tonies had his memories taken and a bomb transplanted in his chest. His life’s purpose is killing the world’s strongest Armed Librarian, Hamyuts Meseta. But, one day he gets his hands on the “Book” of a beautiful princess and falls in love at first sight. Furthermore, that love will cause Colio to get involved in a grand scale battle…

Reincarnated into a land of cultivation, Yuan Zhou uses his Earth knowledge and assumptions to become a genius under the heavens for both business and cultivation. However, he walks the path of defiance, exceeding all rational cultivation bounds. His business ideas struggle against the stagnant culture that pervades the land, but the things he doesn't lack are his drive for immortality and power.