ne large mindless swarm undead 

Perception +18; darkvision

Skills Acrobatics +19

Str -3 Dex +3 Con +4 Int -5 Wis +2 Cha +4

AC  29; Fort +20, Ref +19, Will +16

HP 120, negative healing; Immunities mental, poison, precision, death effects, disease, paralyzed, unconscious; Weaknesses area damage 10, splash damage 10; Resistances bludgeoning 5, cold 10, electricity 10, fire 10, piercing 10, slashing 10

Boneshard Burst When a clacking skull swarm is reduced to 0 Hit Points, it erupts in an explosion of foul energy and bone fragments in a 30-foot burst, dealing 2d12 piercing damage and 2d12 negative damage (DC 29 basic Reflex save).

Chattering Teeth (arcane, auditory, aura, emotion, enchantment, incapacitation, mental) 60 feet. A clacking skull swarm emits a cacophony of chattering. A creature entering or beginning its turn within the area must succeed at a DC 29 Will save or become confused for 1 round. A creature that successfully saves is immune to that swarm's chattering teeth for 24 hours. The swarm can stop or resume this ability as a free action.

Speed 25 feet

Shrieking Scream [>>] (auditory, emotion, enchantment, fear, mental) The clacking skull swarm emits a terrifying, painful scream that deals 10d6 sonic damage to all creatures in a 30-foot cone (DC 29 basic Will save). A creature that fails this save is also frightened 1 (frightened 2 on a critical failure). The swarm can't use Frightening Scream again for 1d4 rounds.

Swarming Gnaw [>] Each enemy in the swarm's space takes 4d8 piercing damage (DC 29 basic Reflex save).

Bestiary 3, page 244.