Walker and Ignus were both forced to fly lower while they traveled. It wasn't that they were unable to fly as high as they had or they were below of mana or anything of that sort. It was the dark clouds of smoke and the falling ash that was causing them more trouble.
Just the air itself was already heavier. The ash within it was making the air taste bitter and generally bad on Walker's tongue. That was aside from the burning acrid smell of smoke going in to his nose. It proved that this air was not safe or good to be breathing at all.
While he could easily manipulate the manas around in to keep the ash and the smoke away from him, others would struggle to do so. That was where magic items like rune sewn cloth could come in though, it would be simple to make some cloth with a light purification rune sewn in.
