MTL - Phoenix Destiny - Chapter 775 Sanctuary

This is a story about the protagonist getting the system, going crazy in the biochemical apocalypse, producing aircraft and tanks, destroying zombies, saving good people and killing bad people.

- Description from novelbuddy

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

Kim Jeongjin, an editor of a publishing company on the brink of closing due to bankruptcy, ends up transmigrating inside a fantasy novel as the incompetent youngest son of a wealthy family.

And here he thought that he should live a rich life in this life…

“Why was I given a high-level skill? Don’t even bother!”

Skyseal Emperor Gu Taxian is perhaps the greatest Emperor in all of history. He crushed the Hundred Empires and brought them to heel, built the vast Great Stone Wall to keep out the deadly wilders, relocated mountains and rivers to promote commerce, set up roads and highways, and even promoted free academies of learning for the common man in an attempt to uplift them. But the Skyseal Emperor’s ambitions involve more than just this – he is preparing to launch a great campaign to stamp out all pagan religions, wishing to allow all men to become like gods instead of merely worshiping them. Deities, demons, and immortals alike tremble and rage at the Skyseal Emperor’s ambitions.