Heaven Official's Blessing Vol. 4 : Manhua - Mo Xiang Tong Xiu

As the sandstorm rages, our heroes take shelter in a cave, where they find a merchant caravan waiting out the bad weather. The cave reveals itself to be the ancient tomb of a general who fought there two hundred years ago - roughly the time when Xie Lian was collecting trash nearby... The merchants are confident that Banyue Pass is safe to cross, so long as they have a skilled guide. But disaster strikes unexpectedly: scorpion-snakes attack the group, one sinking its fangs into a merchant, and another into the crown prince. The antidote lies in the elusive shanyue herb, which can only be found within the walls of the fallen city...