Under the influence of the Chaos runes, Anos Abyss underwent a heavenly change.
The so-called rune was the realization of a concept. Its existence could mean some kind of power. Now, because more and more Chaos forces gathered into the sky, those Chaos forces and the Abyssal rift had released a presence of Dark Abyss that were fused together, turning the entire giant whirlpool into some sort of an outer world itself.
The two presences were the Chaos Void that existed since The beginning of Creation and Chaos destruction when everything had come to an end. The two presences entangled and gave birth to all sorts of horrific changes to the world.
