Volume 33: Where to Go from Here, Chapter 28: Battle for the City (11)_2

Meanwhile, two Black Warrior Kings also moved to the rear of the Windriding Knights' formation to launch an attack, their Bone Spirit Flame Swords swirling and stirring up billowing dust and smoke, shrouding the entire battlefield in layers of thin mist. This was the poisonous fog created from burning putrid bones, lethal when inhaled by ordinary people, and even for those strong in martial arts, easily penetrating through the skin to cause indirect harm.