NPCs composing that spawngroup :

greater_war_boned_skeleton (100%)

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

charasis_125, range=96 (-64,476,22)

a_bottomless_feaster (50%)
greater_war_boned_skeleton (50%)

charasis_126, range=74 (-141,621,22)

a_sepulcher_skeleton (50%)
a_sepulcher_skeleton (50%)

charasis_127, range=45 (-170,532,14)

charasis_128, range=33 (-144,518,3)

a_bile_golem (100%)

charasis_129, range=19 (-116,532,14)

charasis_130, range=80 (-208,549,22)

an_undead_oblation (50%)
greater_war_boned_skeleton (50%)

charasis_205, range=80 (-95,621,23)

a_bottomless_devourer (100%)