Pit of 100 Trials

The ultimate optional challenge in Paper Mario: The Thousand-Year Door is the Pit of 100 Trials. It is found near the entrance to the Palace of Shadow. To complete this area, you must trek through 100 floors, defeat a lot of enemies lurking in the pits and even retrieve some new badges and the Strange Sack along the way. The enemy located on 100th floor is the boss, Bonetail. You can't save throughout the entire Pit.