| Hit Dice: | 4d12 (26 hp) |
| Initiative: | +3 |
| Speed: | 15 ft. (3 squares), climb 15 ft. |
| Armor Class: | 15 (+2 size, +3 Dex), touch 15, flat-footed 12 |
| Base Attack/Grapple: | +2/— |
| Attack: | Swarm (1d6) |
| Full Attack: | Swarm (1d6) |
| Space/Reach: | 10 ft./0 ft. |
| Special Attacks: | Distraction |
| Special Qualities: | Damage reduction 5/bludgeoning, darkvision 60 ft., half damage from slashing and piercing weapons, immunity to cold, swarm traits, undead traits |
| Saves: | Fort +1, Ref +4, Will +4 |
| Abilities: | Str 2, Dex 17, Con —, Int —, Wis 10, Cha 1 |
| Skills: | — |
| Feats: | — |
| Environment: | Any |
| Organization: | Solitary, pack (2–4 swarms), or infestation (7–12 swarms) |
| Challenge Rating: | 3 |
| Treasure: | None |
| Alignment: | Always neutral evil |
| Advancement: | — ♊ |
| Level Adjustment: | — |
With the scrabble of hundreds of bony claws, a mass of tiny skeletal creatures surges across the floor, with pinpoints of red light gleaming in their empty eye sockets.
A bone rat swarm is a mass of undead skeletal rats. Though individually such creatures would pose little risk, in great numbers they can strip a creature clean in short order.
A bone rat swarm seeks to engulf and devour any living prey it encounters. A bone rat swarm deals 1d6 points of damage to any creature whose space it occupies at the end of its move.
Distraction (Ex): Any living creature that begins its turn with a bone rat swarm in its space must succeed on a DC 15 Fortitude save or be nauseated for 1 round. The save DC is Constitution-based.
Turning: See Undead Swarms and Turning.
Source: Libris Mortis, page 88. Added the reference to turning undead swarms.