Carbuncles are minor agents of chaos. They seem to be curious little animals like armadillos, and they feed on leaves and small insects. Set in the carbuncle’s head above its eyes is a large ruby (randomly-determined value of at least 500 gp). If the beast dies, any ruby attached to it shatters and cannot be reconstituted—but it can voluntarily give up its gem, in which case the gem will re-grow over a period of several months (re-roll the gem’s value each time it re-grows). The carbuncle will not normally give up its gem unless charmed or otherwise enchanted.

Carbuncles are empathic and communicate via a minor form of telepathy. They will approach and seek to join a party of humans or demi-humans and then try to spread discord by means of lies, bearing false witness, or betraying the party’s presence to nearby monsters.