My Life Can Be Infinitely Simulated - Chapter 36 - : 036 Found it

"Locke transmigrated into an era where everyone had Battle Beasts. Daemons were rampant and humans were forced to build walls around their dwellings while depending on Beastmasters to keep those monsters at bay.

The Third Miss of the Qin Clan is a useless and timid person. When the Prince withdraws from her marriage, she commits suicide by jumping into the river. In the 21st century, Qin Chu, a genius agent, is framed and his soul crosses over to the Third Miss of the Qin Clan. So what if she’s useless,

Six months ago, tens of thousands of black phantom towers appeared all over the world, floating above the cities. Chemists, physicists, religious people… all of them could do nothing.

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.