The Magic Genius of the Marquis is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

To survive… I have no choice but to become a genius. Starting today, I’ll do well, so please support me. Lee Hyun-woo finds himself possessed by Kyle Seltarion, an extra character in the game where he once reigned as the world’s top-ranked player. Considering the game’s storyline, he faces a situation where Kyle’s death is imminent. What’s worse, he’s now in the body of a character who can’t use magic or aura, has a terminal illness, and has such a nasty personality that his reputation is at rock bottom! However, upon discovering a new talent, he awakens his mana and begins to improve his condition and reputation using the hidden route knowledge he gained through grinding in the game. His immediate goal is to save his own life, but that goal is closely tied to preventing the world’s destruction… To overcome this situation, he needs to gather allies and build his reputation! Let’s leave behind the past as a scoundrel and move toward a new chapter!