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Before us there was an enormous ice cube. Inside of the ice cube there were two monsters from the past. A Chaos Spirit and a Chaotic Beast. From what I've learned, Chaos Spirits are the intelligent inhabitants of the Chaotic Plane, a different dimension where these invaders have come from. Meanwhile, the Chaotic Beasts are like the animals or monsters of such a place.
It seems the Chaos Spirits used Chaotic Beasts as their tamed monsters, using their power to push their invasion over the world of Yggdrasil. Of course, at the end, they were defeated, but many remnants remained, sealed elsewhere, somewhere… Benladann has the power to absorb such remnants and free the world from the chaotic essence they emanate, which in larger quantities could threaten the world as a whole.