The master of the smell of gunsmoke was naturally Fangsheng. As for why he appeared in the Realm of Lust, let us rewind the timeline by about twenty minutes...
Before Helagert City vanished from the timeline, Fangsheng and Millis were desperately fighting off a tide of Magical Beasts! Their armor was already stained red with blood, and the surroundings were littered with the corpses of Magical Beasts!
Just as they were in the midst of the slaughter, a melodious and incomprehensible singing suddenly echoed from the distant horizon. It dominated the entire world, utterly suppressing all other sounds until it felt as though nothing else existed in their minds.
Chapter 156