Inside the Cave of Obscenity - Vol 7 Chapter 1: Footsteps of Collapse

A young surgeon, who is struck by a system, embarks on a bizarre journey of life.

The legend of the continent, the battle that brought fame; the Sacred Phoenix Lady, the Windfire Meteor Godrealm saber-art; the pair that ascend and fuse, the golden sun and the blue moon, the fury of the crashing thunder. There is no magic, no battle qi, nor any martial arts in this land. However, there are martial spirits. Ten thousand years have passed since the founding of the Tang Sect on the Douluo continent, and it has declined. A new, proud generation of heaven’s chosen has been born. Can the new generation of Shrek’s Seven Devils rally the Tang Sect and once more compose the song of the Unrivaled Tang Sect?

Protagonist travels between different anime worlds to right wrongs and uncover his reason for being along the way.

- Description from Novelupdates

At the beginning of the 21st century, twelve reincarnations shattered the void and returned to their hometown.

They preach the world and reopen the space of reincarnation.

Then……

“The Republic of East Asia announced that it will fully implement a five-year spell casting and twelve-year simulation mage training policy.”

“The Republic of East Asia has announced a new change in the marriage law, making it legal to marry someone you call upon after meeting the adulthood conditions of your respective race.”

“The Republic of East Asia announced that the East China Military Region No. 1 Mobile Armor Brigade was established, and the special humanoid mecha “Gundam” officially joined the campaign.”

“Congratulations from the United Kingdom on this, the upper hero Arturia Pendragon will visit Shanghai next month”

“In the far east of Japan, the ignition of the wave engine failed, or seek energy assistance from the East Asian Republic.”

“Space cracks have been discovered in the Chernobyl region, alien creatures have ravaged the Chernobyl region, and the Russian Defense Forces have entered the battle.”

Four years after twelve reincarnators changed the world, Li Ping entered his own battlefield for the first time.

PS: Although the introduction is like this… but in fact it is written about two thorns + machine battle + movie + mythical stew…

- Description from novelbuddy