NPCs composing that spawngroup :

a_coldspine_seahorse (100%)

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

sirens_13, range=72 (-817,-232,-72)

an_enthralled_bulthar (50%)
an_enthralled_bulthar (50%)

sirens_67, range=51 (-827,-214,-72)

an_enthralled_bulthar (50%)
an_enthralled_molkor (50%)

sirens_78, range=71 (-879,-233,-152)

sirens_86, range=64 (-821,-109,-177)

sirens_93, range=50 (-799,-167,-153)

#Ulth_the_Enraged (20%)
an_enthralled_bulthar (80%)

sirens_117, range=17 (-832,-167,-153)

a_coldspine_sea_hors_190190, range=40 (-889,-166,-175)

a_coldspine_seahorse (50%)
a_swordfish (50%)

an_icy_servant_190204, range=40 (-888,-155,-172)

a_swordfish (100%)

sirens_231262, range=0 (-849,-167,-178)

an_enthralled_molkor (100%)

sirens_231263, range=50 (-799,-167,-153)

sirens_231264, range=40 (-889,-166,-179)

an_enthralled_bulthar (15%)
a_servant_sea_elephant (85%)

sirens_231269, range=40 (-888,-155,-172)

a_coldspine_seahorse (99%)
Fellspine (1%)

sirens_231274, range=65 (-833,-230,-72)

a_watery_servant (100%)

sirens_231275, range=51 (-826,-213,-72)