MTL - Heroes of the Invincible Undead - Chapter 2869 emissary

In a world where magic and divine power collide, the youngest son of Lucifer, a demon boy born with unimaginable strength, was chained and sealed away by his father to prevent him from destroying Hell itself. At the age of eight, his power became so uncontrollable that even the King of Hell feared his existence. Desperate to keep the demon's destructive potential contained, Lucifer made a pact with the great Merlin, who trapped the boy in the human realm, binding his powers with enchanted chains.Years later, with Merlin dead and a kingdom still fearful of the demon’s release, an elite group of knights, blessed by the gods, take it upon themselves to guard his prison. However, when a war between the mages and knights erupts, chaos provides the perfect opportunity for the young demon to break free.Hidden among the knights, disguised within their ranks, the demon plots his next move. But his escape is just the beginning. Hunted by both the mages and the knights, he must navigate a world where ancient gods, wizards, and warriors clash. As he travels deep into enemy territory, sneaking into the heart of the kingdom, he is driven by one purpose: freedom.Now, with his powers still sealed but his physical strength unmatched, the young demon embarks on a journey that will shake the foundation of both realms. Can the knights stop him before he regains his full strength, or will the demon's wrath bring both Heaven and Hell to their knees?As the demon hides in the shadows of the human world, a new chapter in the war between gods, magic, and demonic power begins.

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

Waking up in an unfamiliar world with no memories, I had only one advantage—a mind filled with knowledge of fictional tropes, clichés, and common sense learned from countless novels.At first, I thought I was trapped in a romcom nightmare when I started triggering events like “Helping a Girl on a Rainy Day”, “Damsel in Distress”, and “Tripping Into the Heroine’s Arms.” Naturally, I shut those nonsense down before they could escalate. No forced romances. No misunderstandings. No cringe.But something was clearly off.The world wasn’t just a slice-of-life comedy.Beneath the cliché academy setting, there were whispers of awakening powers, hidden dangers, and a brutal magic academy entrance exam.And every challenge I prevented or manipulated was an opportunity to grow stronger.[Title Earned: Background Character.][Achievement Unlocked: Firm Mind.][New Skill Acquired: Background Character's Aura.][New Ability Acquired: Anti-Narrative Influence.]I may be just a background character, but if fate insists on throwing these events at me, I’ll turn them into stepping stones.Let the protagonists play their scripted roles—I have my own path to power.

[The 3000th Descent of Mystery is about to begin.][This is your only chance to redeem yourself.]When the whole world was in danger, Wang Teng activated a unique talent.It was the Rank SSS talent - Inequivalent Exchange!He was not purchasing things for free, but the exchange was not equivalent.[Exchange successfully. You used half a bowl of cup noodles. With your Rank SSS talent, you may retrieve an unlimited supply of cup noodles.][Exchange successfully. You used a bottle of Sad Breeze wine to exchange for the Star Shifting Method.]…From then on, Wang Teng activated a new exchange system.