NPCs composing that spawngroup :

#A_Terror_Wraith (10%)

a_shadow (33%)

plaguebone_skeleton (57%)

NPCs spawning around that spawngroup :
(Max range : 100)

citymist_101, range=96 (-120,-459,75)

citymist_102, range=27 (-116,-566,75)

citymist_103, range=83 (-138,-636,76)

citymist_142, range=90 (-231,-557,3)

Captain_of_the_Guard (10%)
greater_spurbone (90%)

citymist_143, range=68 (-154,-620,5)

an_apparition (50%)
greater_spurbone (50%)

citymist_146, range=41 (-138,-594,3)

an_apparition (100%)

citymist_147, range=45 (-162,-513,5)

citymist_152, range=81 (-100,-483,4)

citymist_162, range=51 (-100,-584,22)