One Piece: The Soul Purchasing Pirate - Chapter 33

A normal office worker, Toru Minasuki, was swallowed up by a dimensional fissure and reincarnated into a different world. Upon reincarnation, Toru was given a [skill board] by God. Make the most of it to acquire all the necessary skills! Even though he is an “inferior person,” he’ll make his way to the top!

Originally from the slums, Adam was chosen as a candidate for an experiment to ignite the Spark - an entity that gives superpowers. However, he failed and was thrown into the Dead Lands - the place the world became after the fall of the Last Star, beginning a new era for mankind, dangerous and unexpected. He faced against monsters and dangerous anomalies, sometimes creating artifacts - the miracle of this world.Killing his first monster in deadly combat, Adam became a Phantom - one who could evolve, endlessly moving toward power.Follow Adam on his journey, from fighting monsters and exploring Dead Lands to endless evolution!

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

I returned after 10 years.