Ultimate Gamer System: Factory Must Grow! - Chapter 19: Building Phase is on, baby!

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.

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

Shi Jin once read a book. It was supposed to be about satisfying the desire for vengeance.

Skyseal Emperor Gu Taxian is perhaps the greatest Emperor in all of history. He crushed the Hundred Empires and brought them to heel, built the vast Great Stone Wall to keep out the deadly wilders, relocated mountains and rivers to promote commerce, set up roads and highways, and even promoted free academies of learning for the common man in an attempt to uplift them. But the Skyseal Emperor’s ambitions involve more than just this – he is preparing to launch a great campaign to stamp out all pagan religions, wishing to allow all men to become like gods instead of merely worshiping them. Deities, demons, and immortals alike tremble and rage at the Skyseal Emperor’s ambitions.