From Pathfinder Claws of the Tyrant, which isn't enabled.

Skeletal Rat Swarm

CREATURE 2

UNCOMMON LARGE MINDLESS SKELETON SWARM UNDEAD UNHOLY

Perception +8; darkvision, scent (imprecise) 30 feet

Skills Acrobatics +8, Athletics +7, Stealth +8

Str +4, Dex +4, Con +2, Int -5, Wis +1, Cha +2

AC 16; Fort +5, Ref +11, Will +8

HP 40, void healing; Immunities bleed, death effects, disease, paralyzed, poison, restrained, swarm mind, unconscious, precision; Weaknesses area damage 4, splash damage 4; Resistances cold 5, electricity 5, fire 5, piercing 5, slashing 5

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

Ravenous Sickness (disease, unholy)

An infected creature can't heal damage it takes from this disease until the disease is cured

Saving Throw DC 20 Fortitude

Stage 1 carrier with no ill effect (1 day)

Stage 2 1d6 void damage and the target requires twice as much food for a creature of their size to avoid starvation (1 day)

Stage 3 1d6 void damage and the target requires three times as much food for a creature of their size to avoid starvation (1 day)

Stage 4 1d6 void damage and the target takes 1 void damage each hour until it eats a full meal (1 day)

Stage 5 dead, rising as a skeleton immediately after it devours the flesh off its own bones.

Swarming Bites

Each enemy in the swarm's space takes 3d4 piercing damage (DC 18 basic Fortitude save). A creature that fails this save is exposed to ravenous sickness.

Pathfinder Claws of the TyrantORC