As a "Gatekeeper" and an evil creature herself, Kardashian naturally knew a great deal about Evil Spirits.
After living with her for some time, Sifa also learned what Evil Spirits were actually like, rather than having only a vague concept of them as before.
Most Evil Spirits were products of the deaths of High Sequence powerhouses. Those of the low and mid Sequences could at most become Wraiths after death, while ordinary people became Phantoms that posed almost no threat.
Of course, "almost no threat" was from a Beyonder's perspective.
Aside from Evil Spirits transformed from the corpses of High Sequence powerhouses, Kardashian had said that a small number were Wraiths that had broken through their inherent limitations by taking advantage of various opportunities.
The transformation of High Sequence powerhouses was relatively common. After consuming potions and gaining divinity, their Spirit Bodies underwent mutations. As a result, even after they died and their powers dispersed, some of their Spirit Bodies remained, retaining many extraordinary qualities and becoming extremely terrifying.
Normally, Evil Spirits weakened with the passage of time until they completely vanished. However, they could assimilate the areas where they had been born, allowing the Spirit World or Underworld to merge with those places. By drawing power from them, they could maintain their existence.
Since this island had been ravaged by the power of death and was filled with it everywhere, it provided extremely favorable conditions for Evil Spirits to exist. Even with the passage of time, they would not weaken here.
In addition, Evil Spirits had their own "territories" and ranges of activity. They could not leave unless they accumulated enough power to fundamentally change the nature of their existence.
However, an Evil Spirit could leave its "territory" by possessing someone. Ordinary people and most Beyonders, though, could not