NPCs composing that spawngroup :

a_lesser_mummy (33%)

a_necro_acolyte (34%)

a_sturdy_skeleton (33%)

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

befallen_54, range=96 (-652,113,-66)

a_greater_skeleton (50%)
a_necro_acolyte (50%)

befallen_110, range=99 (-494,95,-76)

befallen_116, range=80 (-540,85,-39)

befallen_117, range=76 (-591,88,-39)

befallen_119, range=37 (-546,191,-38)

befallen_120, range=57 (-519,130,-39)

befallen_121, range=57 (-511,152,-39)