NPCs composing that spawngroup :

an_apparition (50%)

greater_spurbone (50%)

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

citymist_102, range=66 (-116,-566,75)

citymist_103, range=22 (-138,-636,76)

citymist_142, range=99 (-231,-557,3)

Captain_of_the_Guard (10%)
greater_spurbone (90%)

citymist_144, range=68 (-141,-553,3)

citymist_145, range=86 (-236,-593,3)

Captain_of_the_Guard (10%)
greater_spurbone (90%)

citymist_146, range=30 (-138,-594,3)

an_apparition (100%)

citymist_149, range=76 (-230,-623,23)

citymist_150, range=80 (-234,-626,5)

a_shadow (16%)
plaguebone_skeleton (16%)

citymist_162, range=64 (-100,-584,22)

citymist_163, range=59 (-100,-645,23)