NPCs composing that spawngroup :

a_sepulcher_skeleton (100%)

NPCs spawning around that spawngroup :
(Max range : 200)

charasis_114, range=104 (-42,444,22)

charasis_116, range=185 (7,531,22)

charasis_123, range=194 (3,549,21)

a_bile_golem (50%)
a_bile_golem (50%)

charasis_124, range=82 (-62,429,21)

a_bile_golem (50%)
a_sepulcher_skeleton (50%)

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

a_bottomless_feaster (50%)
greater_war_boned_skeleton (50%)

charasis_126, range=198 (-141,621,22)

a_sepulcher_skeleton (50%)
a_sepulcher_skeleton (50%)

charasis_127, range=112 (-170,532,14)

charasis_128, range=95 (-144,518,3)

a_bile_golem (100%)

charasis_129, range=112 (-116,532,14)

charasis_130, range=141 (-208,549,22)

an_undead_oblation (50%)
greater_war_boned_skeleton (50%)

charasis_131, range=186 (-263,280,22)

charasis_132, range=148 (-221,296,23)

charasis_133, range=13 (-156,429,22)

charasis_134, range=13 (-132,429,22)

charasis_135, range=162 (-243,294,22)

charasis_137, range=193 (-221,246,23)

charasis_138, range=185 (-189,243,22)

charasis_146, range=172 (-6,320,22)

charasis_147, range=170 (12,353,22)

charasis_155, range=198 (-154,224,-139)

charasis_156, range=180 (-136,242,-162)

a_sepulcher_skeleton (50%)
greater_plaguebone (50%)

charasis_208, range=126 (-127,548,4)

greater_war_boned_skeleton (100%)