Dark Warlock in the Apocalypse - Chapter 191: Spare me

When a boy in a medieval fantasy world wakes up with the memories of his past life, he discovers a secret buried deep within his mind—a highly advanced AI companion. This AI, a relic of his previous existence, holds the knowledge of a futuristic world filled with technology, science, and innovation.Armed with this unprecedented advantage, the boy embarks on an extraordinary journey to transform his medieval surroundings into a thriving futuristic utopia. From reinventing agriculture to creating advanced cities, he introduces ideas far beyond the comprehension of his peers. But his vision isn't without challenges—power-hungry nobles, skeptical commoners, and ancient magical forces stand in his way.

A mental patient, or a born policeman?

A peerless genius, or a master of crime?

There are cops who are least like cops, and there are criminals who are least like criminals.

Neither good nor evil is absolute.

It is a grey world we live in.

- Description from Novelupdates

The oldest myth between heaven and earth reappears in the world, countless spaces begin to slowly interweave, and the dark side of the world quietly emerges.

Advocate the friars who are weak in flesh and blood and eternal in spirit. Showing a tyrannical body, there is my invincible martial artist.

Looking at the changes in the world, Lu Ren exhaled in a panic.

“Ding, because of your uninterrupted breathing for 26 years, you suddenly realized something, and successfully realized the breathing technique.”

Hearing the prompt sound in his mind, Lu Ren waved his sword hesitantly.

“Ding, because you were blindly poking a few times with your sword, you suddenly realized something and successfully learned basic swordsmanship.”

After a long time, he looked at the army invading from another world, raised his long sword and slashed it out.

In an instant, the endless air waves rolled back, and the mountains and rivers where they passed collapsed, and the rivers fell.

Then the army was annihilated and bombarded towards the different world. The entire other world was completely shattered by the explosion of infinite fire, and slowly disappeared into the air.

- Description from novelbuddy

…but it seems pretty doable.