Overlord: The Multiverse - Chapter 24: World Championship

A story about a history teacher gaming-addict with familial trauma, and a peculiar woman seemingly stuck out of time and beyond out of touch.The two have been thrust into the weird and whimsical world of Altros, a planet with divides born of very real superhuman strength cursory of an odd ranking system, and, naturally, species differences.Not exactly the best of news for our resident Scottish history teacher whose ears have changed into fox ones alongside his nine new fluffy tails.First though, Darren, or Lone, or whatever else the weird system claims he's called, has to figure out how to live with his new companion Sofia, for seemingly forever while also just barely managing to survive being stranded on a monster-infested island with a self-proclaimed former-immortal who can see despite being blind, can freely teleport, and who also, of course, seems prone to experience bouts of extreme depression.Not an ideal situation when he himself hasn't been in a great headspace for over a decade now. But hey, at least there's an incredibly expansive litRPG system to keep the both of them entertained, right? That'll fight off the fear of death, surely.

He is the ruler of the mercenary realm, an overlord that gives headaches to the leaders of any country! For the sake of his friends, he’s willing to sacrifice himself; for the sake of his family, he does not hesitate to spill blood! He is a dragon, one that soars above even the highest of heavens. He’s a power that advances triumphantly through unstable situations, stirring up both the winds and the waters.

- Description from Novelupdates

Lin Wudao has traversed, and there is an invincible corpse collection system.

As long as you collect the corpses for the strong, you can get the things they owned or touched as rewards during their lifetime, and the obtained items are still strengthened.

Lowest, ten times stronger!

[You collected the corpse of the great emperor Jiang Taichu, and gained ten thousand years of cultivation! 】

[You collected the body of your fiancée Jiang Qingxue, obtained the Zichen Sword, a humane spirit weapon, and after strengthening it ten times, it was upgraded to become an extreme spirit weapon, the Xuantian Ancient Sword! 】

[You collected the bones of an immortal, obtained a ray of immortal origin, enhanced it by 100,000 times, and upgraded it to become the original origin of Hongmeng. After refining it, you can be promoted to the immortal emperor! 】

…

Since obtaining the invincible corpse collection system, Lin Wudao has embarked on an invincible road that can push through the ages and suppress the heavens.

- Description from novelbuddy

A skilled but unfortunate modern-day assassin was killed in a freak accident. However, he soon found himself summoned to another world by an evil wizard, who had him possess the body of a boy as an experiment. After successfully planning the evil wizard’s downfall, he used the wizard’s body as a springboard to gain influence and power in his new world.

- Description from Novelupdates