Guild Wars - Chapter 1 - The Man Who Conquered All

A supreme expert in the Immortal World had died, and a strand of his soul returned to its original body on Earth. Tang Xiu discovered with amazement that ten thousand years passed in the Immortal World, yet only a single year passed on Earth.

Ruthlessly betrayed by his lover and trusted friends, Tang Xiu found that his soul went back to his previous body on Earth, and, despite he spent 10,000 years in the Immortal World, just a year has passed on Earth and many things have changed. Having an unsurpassed knowledge, Tang Xiu will protect his loved ones and go back to the Immortal World to take his revenge.

- Description from Novelupdates

The story is about a a hitman, Who dies because of his own recklessness and transmigrates into a game he used to play after his retirement as a hitman.I'm not gonna spoil any further, but i might answer few of your questions.Is MC overpowered?Nope, he'll become strong over time and all battle he'll fight will be because of his effort and techniques.Is there magic and adventure?Yes! It have both magic like normal isekai with adventure and fighting with monsters and many other things. There are other important things like “Essence Stone” But let's talk about it in the chapters.There will be harem?Not really, He will be in contact with many beautiful female and males but one waifu but i haven't decided yet.All i can say is, give it a try, I'll try my best to make it worth your time.

Lin Xiao Ci transmigrated! Her identity is a female villain in a novel in the ancient times. In order to get close to the male lead, her character has walked the path of seeking death. She decided to stay away from the male lead and his family, cherishing her life. Speedily, she prepared divorce papers and delivered to the male lead who had been set up by the original villain to marry her. “Husband, I would like to turn over a new leaf. In the past I have used you and I have wronged you. Now, I will return you your freedom.” The man snatched and tore the divorce papers into pieces, and fiercely said “Dream on!”

- Description from Novelupdates

Lin Wudao transmigrated and obtained an invincible system to bury corpses.

So long as he buried the corpses of the powerful, he got to take over what they had or what they touched as his bonus. What was more, those items he stood to win were the enhanced versions.

The minimum level was enhanced by ten times!

“You’ve buried the corpse of Jiang Taichu the Great Emperor. Your cultivation prowess just increased by 10,000 years!”

“You’ve buried the corpse of your fiancee, Jiang Qingxue. You get the essence of the immortal, which is enhanced by 100,000 times! It’s thus upgraded into the essence of harmony. You will become the Immortal Emperor after the extraction of it!”

……

Ever since he acquired this system, Lin Wudao had embarked on an invincible journey of advancing history and dominating the world.