NPCs composing that spawngroup :

#The_Crypt_Feaster (34%)

an_undertaker_skeleton (33%)

a_bottomless_devourer (33%)

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

charasis_44, range=136 (-271,45,4)

an_undertaker_skeleton (50%)
a_sepulcher_skeleton (50%)

charasis_55, range=194 (-460,128,3)

a_pulsating_bile (100%)

charasis_58, range=156 (-269,25,4)

a_sepulcher_skeleton (100%)

charasis_96, range=190 (-351,8,14)

a_sepulcher_skeleton (100%)

charasis_98, range=62 (-284,120,5)

a_helot_spectre (100%)

charasis_99, range=199 (-333,-8,15)

charasis_104, range=105 (-368,134,4)

a_sepulcher_skeleton (100%)

charasis_131, range=98 (-263,280,22)

charasis_132, range=125 (-221,296,23)

charasis_135, range=115 (-243,294,22)

charasis_137, range=82 (-221,246,23)

charasis_138, range=103 (-189,243,22)

charasis_139, range=93 (-188,222,22)

charasis_155, range=127 (-154,224,-139)

charasis_156, range=150 (-136,242,-162)

a_sepulcher_skeleton (50%)
greater_plaguebone (50%)

charasis_160, range=185 (-332,6,14)

charasis_161, range=173 (-444,153,4)

charasis_164, range=177 (-443,131,5)

charasis_165, range=55 (-226,152,4)

a_crypt_spectre_189514, range=50 (-237,147,5)