NPCs composing that spawngroup :

an_icy_servant (50%)

a_watery_servant (50%)

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

sirens_13, range=16 (-817,-232,-72)

sirens_61, range=73 (-766,-261,-42)

sirens_62, range=89 (-749,-260,-42)

sirens_67, range=17 (-827,-214,-72)

sirens_78, range=45 (-879,-233,-152)

sirens_91, range=62 (-871,-279,-178)

sirens_93, range=72 (-799,-167,-153)

#Ulth_the_Enraged (50%)
an_enthralled_bulthar (50%)

sirens_117, range=63 (-832,-167,-153)

a_coldspine_sea_hors_190190, range=85 (-889,-166,-175)

a_coldspine_sea_hors_190191, range=65 (-849,-167,-168)

an_icy_servant_190204, range=93 (-888,-155,-172)