The Mage of Eternity - Chapter 737 - : “Found You!”

Warning for lighthearted souls— Expect NTR!! Spicy scenes, lot of Bloodshed and Epic fights.A soul from Earth meets an untimely death due to a mistake from a God. To make up for it, the god grants him a second chance—sending him to a world of fantasy and magic, armed with overwhelming skills and divine abilities. Blessed with the might of a Divine Knight, unparalleled skills, and the strength to power creep all his enemies, his new life is set to be the grand adventure he always dreamed of.However, mixed within his long list of skills and stats is a peculiar trait he never asked for—[Endless Ardor], a Divine Trait that grants him limitless charm and virility. Will his adventure in another world go as he wished for?Follow Reinhardt as he journeys through a world overrun by Demons while spending nights with peerless beauties along the way.

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

The mortal body, metamorphosis, longevity, immortality, and eternal life. These five realms, step by step, reveal themselves in front of you. As a normal person, how can one try step by step to reach and open the door to eternal life?

Between the heaven and the earth lies the mortal body, the mysteries of metamorphosis, freedom of longevity, the power of immortality, and the hope of eternal life. A story filled with endless new magic, a new world of immortal styles, people, demons, gods, fairies, magic, kings and emperors. A world of love and hatred, revenge, and mystical battle, all in “Eternal Life.”

- Description from Novelupdates