NPCs composing that spawngroup :

a_shadow (25%)

plaguebone_skeleton (25%)

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

citymist_54, range=94 (133,-353,39)

a_fog_golem (34%)
a_rambling_fanatic (33%)

citymist_56, range=37 (262,-334,-14)

greater_war_boned_skeleton (33%)
greater_war_boned_skeleton (34%)

citymist_58, range=54 (265,-387,-13)

greater_plaguebone (25%)

citymist_59, range=35 (262,-354,39)

citymist_60, range=78 (225,-426,39)

a_fog_golem (33%)
a_lost_one (33%)

citymist_61, range=98 (130,-364,-13)

citymist_87, range=91 (136,-342,275)

citymist_88, range=55 (199,-396,275)

citymist_92, range=91 (162,-284,76)

citymist_93, range=68 (212,-281,76)

citymist_94, range=30 (249,-327,77)

citymist_116, range=54 (182,-378,65)

citymist_117, range=12 (214,-349,64)

citymist_125, range=38 (259,-369,255)

gyrating_goo (50%)
gyrating_goo (50%)

citymist_127, range=21 (219,-328,274)

citymist_128, range=44 (189,-325,274)

citymist_129, range=67 (201,-286,275)

greater_war_boned_skeleton (25%)
greater_war_boned_skeleton (25%)