The Silt Cave

The Slit Cave is a large salt cave where Rochiear (an enormous rock turtle) resides, located east of the Temple of Trials and the western region of the Lower Wilderness. It is not really a dungeon - rather an instanced map where you can fight Rochiear several times in a day to test your skills, and collect Large Rocks, which is commonly used in furniture crafting.

The recommended level is 35, however you can fight him as a group (up to 5 players), allowing for a level range between 32 and 35. Adventurers above level 35 will be scaled down automatically to level 35 (cannot go any higher or lower). Facing him as a group increases his health pool and difficulty, while on solo he is weaker (due to the Restrained debuff), and you are given a special accommodation for healing.