MTL - Fairy Tail: The Nameless Grim Reaper - Chapter 12 Gerald's mutation...

Qin Tian accidentally transmigrated into a sickly body, a body with broken Dantian that was unable to practice Qigong, in another world. Fortunately, God had mercy on him by giving him a level up system. Useless? That was him in the past. Not worrying about practicing Qigong, he was now able to kill Monsters to level up. Easy! Level up when killing Monsters; level up when killing people. An unbeatable sovereign of the clan in the eyes of other people, but in his eyes, he is a glittering big BOSS.

With this level up system, he will no longer encounter any bottlenecks during a breakthrough in cultivation like other geniuses; all he needs to do was kill as many monsters, clan heads, sovereigns, world experts … to have a better life.

Dedicating his life on a road to become an expert.

- Description from Novelupdates

Demons, devils, ghosts and monsters

Plunge the mortals weak in horrors;

Arms of gods and blades of devils,

Shroud the world in untold evils.

Lu Sheng was an ordinary civil servant in the modern world. After waking from a drunken stupor one day, he found himself trapped in a dangerous world where demons, ghosts and supernatural monsters terrorize the land.

In this world, ordinary mortals live in dark fear and helplessness, without any means to fight against the supernatural.

As Lu Sheng struggles desperately for survival, he stumbles upon a game mod he had designed for a mobile phone app in his previous life. It unexpectedly becomes his special ability, which enables him to instantly level up any skill he learns, albeit at a cost.

Thus, Lu Sheng begins his journey, striving for power beyond the reach of a mortal as he treads the way of the Devil…

- Description from Novelupdates

He returned with a vigorous presence, equipped with a Heaven-reaching Innate Ability. He could heal, tell fortunes, refine medicines, set formations, and refine talismans… “There’s nothing in this world that I can’t do!” — Shen Feng.

A ritual gone wrong gave him the world's deadliest Class—now all he wants is blood.Zeth stole the most powerful ritual magic in the world from a mad cultist. A Class that's fueled by the blood of his enemies and human sacrifice. One that's illegal to use, punishable by gruesome death. And now that he has it, he's faced with a choice: hide away for the rest of his life from those who would hunt him down, or embrace the power, becoming the hunter to get revenge on the murderer that stole his friends' lives.For Zeth, that's no choice at all.His enemies have to die. And he plans to use every drop of blood, eldritch ritual, and demonic summoning he can to kill them.