Aspis

Aspis are weevil-like insects. They are Aberrations from the Far Realm that enter Tol through burrows that they make between the worlds. Luckily, other Far Realm inhabitants find Aspis burrows impossible to negotiate.
Aspis like to create underground warrens, preferably under cities or in the Underdark. As long as there is easy access to food (meat, specifically), they are happy. They are a Hivemind creature, sharing thoughts and personality among the entire warren and communicating largely telepathically. Although they possess a spoken language, it is almost impossible for non-Aspis to learn to speak it. Their Hivemind makes them particularly difficult to affect with Psionics.
Aspis come in three known varieties. When born, they are larvae, and they tend to congregate into swarms in order to better hunt or protect themselves. As they mature, 99.9% become drones. Drones are humanoid in shape, capable of wielding two shields and two swords, or dropping to all fours to scuttle at greater speeds.
Once in a great while, a single Aspis is born and matures into a cow. Cows are nearly immobile, but they are capable of giving birth to more Aspis. They are also capable of spraying an acidic slime that they and their children are immune to, and which they use to coat their lairs and make them more to their liking.
Aspis are considered a terrible danger to Tol in general. The Fire Wasps rooted out a colony from under the town of Shellcliff in 1080 SKR. It is to be hoped that they will not soon resurface again.