NPCs composing that spawngroup :

greater_spurbone (50%)

greater_spurbone (50%)

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

citymist_127, range=50 (139,19,273)

a_mist_golem (50%)
greater_war_boned_skeleton (50%)

citymist_50076142, range=89 (13,49,28)

a_fog_golem (50%)
a_vapor_golem (50%)

citymist_50076165, range=25 (116,-1,3)

citymist_50076170, range=35 (80,-29,273)

gyrating_goo (100%)