NPCs composing that spawngroup :

an_inactive_trap (16%)

a_blast_of_heat (16%)

a_low_hum (16%)

a_magi_construct (16%)

a_singularity (16%)

a_spike_trap (20%)

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

necropolis_14, range=29 (-201,-1015,-255)

necropolis_19, range=187 (-225,-1181,-311)

an_entropy_serpent (50%)
an_entropy_serpent (50%)

necropolis_39, range=166 (-237,-845,-256)

a_Chetari_Deathbinder (50%)
a_Chetari_worker (50%)

necropolis_54, range=88 (-180,-912,-256)

a_Chetari_Dominator (50%)
a_Chetari_worker (50%)

necropolis_61, range=122 (-262,-1088,-288)

an_entropy_serpent (50%)
an_entropy_serpent (50%)

necropolis_72, range=168 (-137,-1164,-281)

an_entropy_serpent (50%)
an_entropy_serpent (50%)

necropolis_162, range=131 (-274,-911,-255)

a_Chetari_Deathshaper (100%)

an_inactive_trap_190081, range=173 (-292,-871,-248)

an_inactive_trap_190083, range=57 (-233,-999,-248)