I am a Gao Fushuai Villain - Chapter 507:

Born into a wealthy family, Gu Shenwei was spoiled and carefree. However, at the age of 14, his entire family were brutally murdered, and he was caught by some bandits who sold him into slavery. As a slave boy, he entered Golden Roc Fort by chance and found the man who had slaughtered his family. He endured insults and worked hard to improve his kung fu while working as a slave boy. He learned from and plotted against his enemy under the enemy’s nose. He became increasingly ambitious as he became more and more powerful. He would only be satisfied if he completely destroyed his enemy—by fair means or foul. Gradually his bitter experience turned him into a totally different person.

In a world where human and monsters relied on mystical fruits and their inner power to fight for dominance, a lost soul was thrown, given the powers from all the other worlds he’s known. But there was a catch; he had no control over what power he would get! With knowledge beyond that of most, he sails his path to the top of the one piece world!

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.

The most precious things in the world are priceless. Ordinary men tend to turn a blind eye to this fact. Apart from the treasured air, sunlight, and familial love, there is still one more thing that’s extremely valuable. It’s right beside you and can be easily obtained.

- Description from Novelupdates