From Pathfinder Society Scenario #7-08: The Haunted Corridor, which isn't enabled.

Recently Slain Rat Swarm

CREATURE 3

LARGE MINDLESS SWARM UNDEAD UNHOLY

Perception +9; darkvision

Skills Acrobatics +11, Athletics +7 (+9 to Climb or Swim), Stealth +9

Str -2, Dex +3, Con +1, Int -5, Wis +1, Cha -3

Slow

A partially decomposed rat swarm is permanently Slowed 1 and can't use reactions.

AC 17; Fort +5, Ref +10, Will +6

HP 31, negative healing; Immunities bleed, death effects, disease, paralyzed, poison, precision, unconscious; Weaknesses area damage 3, vitality 5, splash damage 3; Resistances physical 6 (except bludgeoning)

Void Healing

A creature with void healing draws health from void energy rather than vitality energy. It is damaged by vitality damage and is not healed by vitality healing effects. It does not take void damage, and it is healed by void effects that heal undead.

Speed 30 feet, climb 10 feet

Frenzied Bites

Each enemy in the swarm's space takes 2d6 piercing damage and must attempt a DC 20 basic Reflex save. A creature that fails its save is exposed to zombie plague.

Zombie Plague (disease, divine, void)

The sickened and Unconscious conditions from zombie plague can't end or be reduced until the disease is cured.

Saving Throw DC 17 Fortitude

Stage 1 carrier with no ill effect (1d4 hours),

Stage 2 Sickened 1 (1 day),

Stage 3 sickened 1 and Slowed 1 (1 day),

Stage 4 unconscious (1 day),

Stage 5 dead

Pathfinder Society Scenario #7-08: The Haunted CorridorORC