Inside the Cave of Obscenity - Chapter Volume 4 1: Monster 1

A man is reborn into the world of Avatar: The Last Air Bender as a waterbender from Katara's tribe. Best of all, he was the same age as her, and he had a system with him to help.He knows the future and a system that lets him continuously get stronger by completing quests or long-term missions, as well as giving him the ability to copy abilities from others for himself. He will become invincible in the world of Avatar, even more so than the Avatar himself.

A decision can destroy the sun, moon and stars. A finger can kill the Heavenly Overlord. While chatting, the Heaven and ten worlds can be annihilated.

A poor little kid walks out from a remote mountain area while holding the Nine Dragons and the Incredible Cauldron. With a control over the time and space eternally, he embarks on the Path to God where he defies the odds of the boundless universe gaudily by fighting against royalty and clashing with the legendary generation.

- Description from Novelupdates

Fate, a gatekeeper who had been working for the castle, is beset by a few burdens.

It’s the beginning of the Apocalypse, and zombies are running rampant over the Earth.