Omnivorous rodents that attack as a swarm

These omnivorous rodents thrive almost anywhere. Normal rats attack as a swarm; each point of damage done to the swarm reduces their numbers by one animal. Any rat bite has a 5% chance of causing a disease. A character who suffers one or more rat bites where the die roll indicates disease will sicken in 3d6 hours. The infected character will lose one point of Constitution per hour; after losing each point, the character is allowed a save vs. Death Ray (adjusted by the current Constitution bonus or penalty) to break the fever and end the disease. Any character reduced to zero Constitution is dead. See Constitution Point Losses in the Encounter section for details on regaining lost Constitution. * Note: The XP award for normal rats is for driving away or killing an entire pack of normal size. If the adventurers are forced to flee, the GM should award 3 XP per rat slain.

Multitudinous, disease-ridden rodents that will eat anything. Avoid contact with humans, but may attack if defending their nest or if summoned and commanded by magic (e.g. see Wererat).