Rocnar

A Rocnar is an Oubliette trap. It takes 83 Construction to build. During Challenge mode, the Rocnar is a Level 97 monster with 100HP that has a max hit of around 11. As a saw is not required to 'build' a Rocnar, the bonus from the Crystal saw will not work.

Trivia

 * Its name is "Rancor" spelled backwards; Rancors are large, hulking aliens featured in the  films that are often used to guard fortresses or treasures or serve as traps.