Tonguetwisters are mountain dragons which are un-trainable. They are mentioned in several books, always against the Vikings, but most notably in How to Steal a Dragon's Sword. They definitely sided with Furious during the dragon rebellion.

Traits and Abilities

This dragon's signature trait is its long, muscular, and flexible tongue. It is able to rend prey and enemies from limb to limb with this tongue. They have acrid black saliva, as many of the dragons do. They have multiple eyes as evidenced in their pictures. They are also said to have X-ray vision in The Complete Book of Dragons.

Tonguetwisters are able to speak Dragonese.