NPCs composing that spawngroup :

#Overseer_Dlubish (10%)

a_goblin_backbiter (13%)

a_goblin_blightcaller (4%)

a_goblin_boneseer (4%)

a_goblin_dirttracer (8%)

a_goblin_flashdrowser (4%)

a_goblin_slavedriver (27%)

a_goblin_stalagknight (24%)

a_goblin_stonechanter (4%)

a_goblin_warder (2%)

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

nurga_102, range=98 (-1475,1539,-300)

a_goblin_overseer (50%)
a_goblin_overseer (50%)

nurga_160, range=2 (-1568,1506,-300)

a_goblin_death_caster (50%)
a_goblin_spirit_chanter (50%)

nurga_163, range=73 (-1528,1566,-300)

a_goblin_blackguard (50%)
a_goblin_overseer (50%)

va_nurga_508003, range=74 (-1525,1565,-300)