A city-slaughtering sacrifice. The Water God Believers' madness was appalling, but not incomprehensible.
Su Zhou, at least, immediately understood why the evil thoughts clinging to the Armored Soldiers and Elite Tier Professionals he had seen were as dark and condensed as those of a Demon Army and its Demon Generals who had pillaged and plundered for a century, weighed down by countless Curses.
He figured that in places he didn't know of, they must have already slaughtered other Shelter Cities, or perhaps some small settlements in the Maze, using those lives as sacrifices.
As for the reason, it was simply to restore their God's power and to completely eliminate any potential resistance. They probably lacked the time and patience to manage a large city, so it was easier just to kill everyone.
