NPCs composing that spawngroup :

a_greater_skeleton (50%)

a_sturdy_skeleton (50%)

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

befallen_47, range=73 (-512,-79,-66)

befallen_46, range=67 (-480,-94,-67)

befallen_92, range=92 (-372,7,-39)

befallen_96, range=54 (-437,-82,-40)

a_necro_neophyte (50%)
a_zombie (50%)

befallen_97, range=92 (-416,-114,-39)

a_lesser_mummy (50%)
a_sturdy_skeleton (50%)

befallen_99, range=94 (-392,-100,-38)

a_greater_skeleton (50%)
a_lesser_mummy (50%)

befallen_100, range=80 (-488,-105,-38)

a_large_plague_rat (50%)
a_necro_neophyte (50%)

befallen_105, range=98 (-552,-54,-39)

a_dread_bone (50%)
a_shadowknight (50%)

befallen_109, range=70 (-438,37,-75)

ice_boned_skeleton (50%)
ice_boned_skeleton (50%)

befallen_111, range=40 (-470,7,-72)

befallen_112, range=62 (-401,-2,-67)

befallen_113, range=51 (-465,20,-39)

befallen_114, range=56 (-400,-41,-38)

befallen_115, range=78 (-449,47,-38)