NPCs composing that spawngroup :

imp_defender (50%)

imp_vanquisher (50%)

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

soldungc2780001, range=159 (832,-446,15)

the_Firewatcher (100%)

soldungc2780010, range=197 (705,-543,24)

#Culthor_the_Gatekeeper (100%)

soldungc2780011, range=197 (680,-542,16)

a_fiendish_guardian (100%)

soldungc2780012, range=172 (703,-518,16)

a_fiendish_guardian (100%)

soldungc2780045, range=190 (796,-515,14)

a_lava_beetle (100%)

soldungc2780049, range=117 (797,-422,14)

a_lava_beetle (100%)

soldungc2780050, range=58 (763,-326,16)

a_cinder_scavenger (100%)

soldungc2780051, range=71 (778,-358,14)

a_cinder_scavenger (100%)

soldungc2780052, range=116 (824,-353,15)

a_cinder_scavenger (100%)

soldungc2780053, range=127 (829,-307,16)

a_cinder_scavenger (100%)

soldungc2780054, range=153 (861,-330,8)

a_lava_beetle (100%)

soldungc2780078, range=153 (596,-241,4)

imp_defender (100%)

soldungc2780196, range=168 (543,-380,16)

imp_guardian (50%)
imp_vanquisher (50%)

soldungc2780197, range=166 (542,-342,12)

#Pulsating_Pool_of_Magma (50%)
a_burning_mire (50%)

soldungc2780198, range=125 (588,-381,14)

a_blistering_horror (50%)
a_smoldering_abomination (50%)

soldungc2780200, range=75 (726,-419,12)

imp_guardian (100%)

soldungc2780201, range=76 (703,-422,10)

imp_vanquisher (100%)

soldungc2780203, range=98 (611,-329,11)

a_conflagarant_terror (100%)

soldungc2780204, range=156 (813,-461,11)

a_smoldering_abomination (100%)

soldungc2780221, range=115 (598,-310,2)

soldungca_fiendish_guardian003102783696, range=179 (724,-525,16)

a_fiendish_guardian (100%)