MTL - Sword Among Us - ~ Big killing (recommended)

With his engagement at hand, the most terrifying and legendary person of the legal world, Fu Huai’an, returns with a son.

Ling Xiao was a powerful martial expert who fell in battle and was unexpectedly transmigrated into another world. He began life anew in the body of a boy with the same name, a fallen genius of the Ling Family whose cultivation had been crippled in a surprise attack, and son to a father who had also suspiciously been crippled under similar circumstances. Armed with knowledge from his previous life, Ling Xiao aim to restore his strength and establish his place at the top of this new world

- Description from Novelupdates

Wang Yanqing’s father died in battle. She was adopted as an orphan by the Marquis of Zhenyuan. She loved Fu Tingzhou for ten years and would go through fire and water for him. However, this woman carried a family history full of scars, and ultimately, Fu Tingzhou sought another woman to marry.

An ordinary student, a wretched peeper, a cowardly teenager with a kind heart. In a terrorist attack, he inherited the knowledge of countless elites, embarked on a path of God Jagged Tu…

He is an artist!

He is a mathematician!

He is a psychology Doctor!

He is a master of fighting!

In fact, he is a man

Taken off raw site:

A wretched, dirty young man is working during the summer when he was caught up in a mysterious explosion. After that explosion, the young man is then left with the memories and knowledge of dozens of the world’s experts.

He has changed, his heart has become cold, iron-blooded. He became a killing machine, his mind turned mechanical, calculative. Everything goes according to his plans and calculations!

In this magical, slaughterous world, a door is opened for him…

- Description from Novelupdates