Don't Call Me Despicable, I Just Want to Kill My Natural Enemies

[Traveling through another world] [Cunning male protagonist] [Multiple world fusion] [Natural enemy] is a word born in nature, just like an insect is to a bird, a rat is to a cat. For a specific species, natural enemy means invincibility. And the natural enemy of human beings is exactly that [? ? ? The male protagonist traveled to a medieval world where human beings were forced into a desperate situation by natural enemies. Humanity was on the verge of being destroyed at any time. What the male protagonist does is to find ways to kill the natural enemies of mankind. If one world alone cannot resist, then the other world and the humans in the other world will be dragged into this war against the natural enemies. If one is not enough, then two; if two is not enough, then three... Vampire hunters, future soldiers, savages, disease doctors, inhabitants of nature, superheroes, cults... Nine worlds that were all human beings but gave birth to different civilizations were merged together. But with the integration of the world, human beings' natural enemies have also expanded to nine... How to make natural enemies fight each other has become the key to this war...