Rush thunder stone

After refining the guest halt stele in Eighty-Eight True Yang Building, Fang Yuan can take treasures from one crystal-wall section without paying an exchange price. One such treasure is a rush thunder stone. He returns it to the wall so the inventory count stays unchanged. ^{ch. 559}

Rush thunder stone is a rare Gu refinement material, nearly extinct and sold only once in a while even in treasure yellow heaven. It is created from the essence of lightning and thunder when the thunder in the nine heavens explodes together. After the immemorial era, seven of the nine heavens fell and only white and black heaven remained, so clashes became rare and production fell drastically. When thunder path flourished, large numbers of rush thunder stones were used to refine Gu, leaving little stock later. As thunder path changed, those stones were no longer needed for ordinary work. Interest remains mainly among Gu Masters or Gu Immortals researching immemorial thunder path Gu worms. ^{ch. 559}