Death March kara Hajimaru Isekai Kyusoukyoku (WN) - Book 17 - 17-13. Changing World 2

The legendary Qin Chen from the Tianwu Continent accidentally fell into the Martial Domain because of his friend’s betrayal.

Three hundred years later, he was reincarnated on an illegitimate son of the royal palace who had been bullied.

He used his previous life accomplishments, concentrating on his skills, refining the pill, and rising against the sky, rising strongly, and embarking on a shocking journey that shocked the mainland.

- Description from MTL

This novel is also known as Gu Daoist Master

Humans are clever in tens of thousands of ways, Gu are the true refined essences of Heaven and Earth.

The Three Temples are unrighteous, the demon is reborn.

Former days are but an old dream, an identical name is made anew.

A story of a time traveler who keeps on being reborn.

A unique world that grows, cultivates, and uses Gu.

The Spring and Autumn Cicada, the Venomous Moonlight Gu, the Wine Insect, All-Encompassing Golden Light Insect, Slender Black Hair Gu, Gu of Hope…

And a great demon of the world that does exactly as his heart pleases!

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*Gu (蛊) referred to poisonous insects in various cultures in South China while in folklore Gu spirits could transform into all kinds of species.

- Description from Novelupdates

With the revival of spiritual energy and the breakdown of the order of species, it is a difficult test whether human beings can still stand at the top of the biological chain.

(There is already an old book, The Strongest Descends in the City, you can read it.)

- Description from novelbuddy

Two years ago, the mere fifteen-year-old scion of the Lin family, in front of the colossal behemoth that is the Murong clan, made a vow!Two years later, no one knows what he has gone through, but from the moment of his return, he radiates a brilliance that seems to compete with heaven and earth!(Note: The protagonist of this book is very aloof, cold, and passionate. Those who like to read about a military king's ambiguous romances and flirts, please bypass this one.)