Source: Dungeons and Dragons
Location: Dungeons mostly
Threat Assessment: 3. Not a skilled fighter. It's real danger is its touch rusts metal to dust. So an encounter with one will disarm most fighters generally in a very hostile environment.
Limitations: Dumb as a stump. Arrows work well.
Personal note: Not sure where this beastie is taxonomically. It seems to have some crab like features along with reptilian. I do remember a child's toy in a 1.99 bag of dinosaurs that was the spitting image of one. Interesting, no?