In the world of Xianxia there has been always a fight between the protagonists and villains. The protagonist that has a cheat of luck, fate, incredible items, physique, or companion. And The villain that has been awakened and given memories of the future and gained a system, due to the villains awakening a system and learning about their fate they're becoming more and more powerful and is always winning against the protagonists.
Due to that, the balance has been offset, due to the worlds' respective protagonist dying the world is becoming more and more vulnerable to disasters, destructions caused by evil, invasions of system users and many other things. So the world wills has gathered and created a system to battle the villains that has a system but they also need someone with a lot of knowledge about this particular battle.
So they choose one world that is neutral and doesn't use the common defense, that is that they're not using a protagonist at all. This is where our protagonist who seemingly awakens as a protagonist(of what kind? it's yours to decide) and seeing the system he knows that he is up against a villain with a system as well.