Reborn: Revenge of the Concubine's Daughter - Chapter 380 - The husband consumed the servant and the servant coveted the husband

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

The year 1847

Nagi Travers, a 20-year-old shut-in and former gaming champion, lives a miserable and isolated existence after being tormented by bullies throughout his life. Fired from his last job and grieving the loss of his parents, Nagi now survives by playing video games and barely ventures outside. His world spirals further into despair when he encounters Jake and Mary, his former high school bullies, who humiliate him and steal his money.Broken by the return of his tormentors and the weight of his past, Nagi contemplates suicide as his only escape. Just as he’s about to take his life, a small girl’s ball rolls into the street, with a speeding truck barreling towards her. In a moment of selflessness, Nagi rushes out and saves the girl, sacrificing himself in the process. Fatally injured, he reflects on the idea that it's better to die doing good than bad.Nagi awakens in a surreal, white world, where he is greeted by an angelic figure who offers him two choices: remain in eternal peace, free from suffering, or be reborn in a different world where he could seek redemption and a second chance at life. Nagi faces a life-altering decision—rest forever or attempt to find meaning and fulfillment in another world.

Qin Tian accidentally transmigrated into a sickly body, a body with broken Dantian that was unable to practice Qigong, in another world. Fortunately, God had mercy on him by giving him a level up system. Useless? That was him in the past. Not worrying about practicing Qigong, he was now able to kill Monsters to level up. Easy! Level up when killing Monsters; level up when killing people. An unbeatable sovereign of the clan in the eyes of other people, but in his eyes, he is a glittering big BOSS.

With this level up system, he will no longer encounter any bottlenecks during a breakthrough in cultivation like other geniuses; all he needs to do was kill as many monsters, clan heads, sovereigns, world experts … to have a better life.

Dedicating his life on a road to become an expert.

- Description from Novelupdates