The Strongest Undead Evolution System

Traveled to the world of the dead and became a cannon fodder-level skeleton soldier? Link suddenly felt a lot of pressure! Fortunately, he has the "strongest undead evolution system" in his body. As long as he kills undead creatures and obtains the "origin of the undead", he cannot evolve infinitely and keep upgrading! Since then, there has been an alien existence in the world of the undead! What? Have you ever seen a skeleton who knows martial arts? Then I will open your eyes! What? Have you never heard that a skeleton can summon an army of the undead? Then I will let you learn a lot! Let's see how a little skeleton evolves step by step, and finally steps onto the supreme throne of the God of the Undead!