Okami Wa Nemuranai - Chapter 8.5

We are born free; yet, why do the deities and Buddhas claim supremacy!Bodhisattva, Buddha, Deity? ... I shall wipe out all your Divine Souls!If the heavens obstruct me, I will shatter these heavens; if the earth obstructs me, I will crush this earth!Tathagata, today you must return to me—five hundred years!...

An ordinary sect cultivator, with the help of the immortal mansion, gradually grew up in the cruel world of immortality, and his mind and body transformed together.

Mortal flow, partial dark wind.

- Description from novelbuddy

Worlds overlapped, and Alien Species descended.Strange entities emerged one after another, as the shadow of evil spread wildly.The calm of life was shattered, and Zhang Xiaoman, inside a fish's stomach, accidentally consumed a system named “World-saving Plan”.From then on, he became the only person among all humans with Extraordinary Power.…Inventing an ancient oath, he established a unique methodology, Cultivated Dark Energy, founded an organization, took Control of the Transcendent, and resisted invasions.Well, this is actually the story of how a Big Con Man bluffed his way into saving the entire world.PS: Contains elements of the behind-the-scenes, Cthulhu mythos.