The material below is Open Game Content from a 3PP Source
A squirming, roiling mass of squeaking rats draws closer, teeth flashing and claws scratching everything in its path.
Rat Swarm CR 2 (XP 600)
N Tiny animal (swarm)
Init +6; Senses low-light vision, scent; Perception +8
AC 14, touch 14, flat-footed 12 (+2 Dex, +2 size)
hp 16 (3d8+3)
Fort +4, Ref +5, Will +2
Defensive Abilities swarm traits
Speed 15 ft., climb 15 ft., swim 15 ft.
Melee swarm (1d6 plus disease)
Space 10 ft.; Reach 0 ft.
Special Attacks disease, distraction (DC 12)
Str 2, Dex 15, Con 13, Int 2, Wis 13, Cha 2
Base Atk +2; CMB —; CMD —
Feats Improved Initiative, Skill Focus (Perception)
Skills Acrobatics +6, Climb +10, Perception +8, Stealth +14, Swim +10; Racial Modifiers uses Dex to modify Climb and Swim
Organization solitary, pack (2–5 swarms), or infestation (6–12 swarms)
Disease (Ex) Filth fever: Swarm—injury; save Fort DC 12; onset 1d3 days; frequency 1/day; effect 1d3 Dex damage and 1d3 Con damage; cure 2 consecutive saves. The save DC is Constitution-based.
A rat swarm typically consists of a biting, roiling mass of hundreds of disease-ridden rats driven to uncharacteristic heights of aggression by fantastic and overwhelming hunger. In such numbers, they become voracious hunters, capable of killing a full-grown human with hundreds of bites. Rat swarms are often found in the sewers of large human settlements.
Rat swarms surround and attack any warm-blooded prey in their path.