This is, of course, not true... The truth can be found with a DC:35 Knowledge (Arcana), (Nature), or (Planes) check (Hey, if it were easy, everybody would be doing it!) The Primal Darkling, the original aberration, has begun to exercise its influence upon this world, through the Systemics of Simultaneous Simularity, allowing it to bridge the gap between worlds through regions of similar geography (which, unfortunately for the folks inhabitting the Aranrath, the region of this world which most closely matches that of the previous world up the Chain of Creation, is their homeland)!
One by one, world by world, the Primal Darkthing has been devouring planets, down the chain of creation, until... now... the Aranrath has been infected. Soon, no doubt, other regions, and then even other regions on other worlds, will be tainted, as well, until the Universe is destroyed...
And then, the Primal Darkling will move on to the next Universe...