The Terminally Ill Young Master is the Mad Dog of the Underworld - Chapter 204

One of the Conferred Martial Emperors, Gu Feiyang, passed away in the Tiandang Mountains and was reincarnated 15 years later as Li Yunxiao of the State of Tianshui, embarking on a heaven-defying journey against the innumerable geniuses of the time.

The nine levels of the Martial Art; the Divine Realms of the ten quarters. From then on, the whole world fell into chaos!

Seo Tae Hyuk, jailed after being falsely accused.

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

Hit by a truck as a young man, after winning God’s ultimate lottery prize, I got to create a HOLY sh*t-like cheat ability of my choosing, create a harem, make loads of money, sleep with a random babe, and do anything I liked; it’s that kind of story.