Four souls were just obliterated into nothingness as if they didn't matter...as if they weren't living breathing people at some point.
Jin Wang already expected to see something like that but the brutal nature of the spell and its mechanism left him appalled.
Killing a person was not nearly as bad as destroying their soul. They could still be reborn after death and have a chance to atone for their sins or suffer in purgatory until they were washed clean.
But to destroy a soul meant that you would be eliminating all of their possible futures, everything they could have done or achieved was now forever lost. It was a sin greater than any, one that would leave its mark for eternity.
As soon as the soul dust settled, another four souls were automatically pulled in and turned into dust for the magic circle. This process not only continued but was also sped up tens of times.