The Speedrun Manual of Miss Witch - Chapter 45 - A Vision of the Other Side? (Part 2)

Every time he dies, Ethan Hill gains a little more power.Earth was chosen for Integration, but Ethan knows from the second his Trial begins that the Integration is a lie. These creatures giving Earth the 'honor' of access to their Interface want something from Earth - he just doesn't know what.Now he's trapped on an alien planet and lost in a time loop, fighting for strength and for his own humanity.One thing's for sure: He'll die as many times as it takes to tear it all down.

Born with a seed of immortality, he rose from the Han tribe at the end of the century, and embarked on the road of immortality, step by step, until he reached the other side of immortality.

Efforts will pay off. For cultivators, what better golden finger is there?

- Description from novelbuddy

In the vast and boundless continent Cangtu, there were ancient sects governing the Ten Old Domains, unworldly immortal clans beyond the Blue Sky, and primordial demon gods dominating the dark abyss that together created a great number of brilliant stories over the long course of the history.

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