It didn't need to be explained why the first possibility was so fear inducing. Even the oldest clans on the mortal plane currently were only the Nephilim. Though their bloodlines were incredibly ancient, they themselves had only begun to appear during the transition between the Golden Era and the Modern Era. Of course, their territory itself was even more ancient than this, but they had only existed for a few million years at best.
However, the last descent was easily trillions of years ago. The descent before that was even more exaggerated. To survive that kind of time, just what level of planning was involved? Just what kind of power backed this endeavor? Just who were the Mist clan originated from?
If this wasn't already shocking enough, the next possibility was only worse.
Dyon had only experienced a single clan exiting the ancient battlefield, and that was the celestial beasts!