Tomb of Madness
The Tomb of Madness is a legendary location in the Underdark. Its location is different in each myth – some believe that it only appears at certain times in certain places, others believe that it shifts continually around the Underdark, while still others believe that those who have visited it have emerged too mad to remember where they truly encountered it.
The legends all agree on one terrifying fact, though: the Tomb of Madness is a place where the Far Realms touch the Mortal world far too closely. Horrific aberrations are normally found near the Tomb, as are changes to the normal laws of reality. The lore speaks of a tremendous treasure hidden in the Tomb, but none who have entered have ever emerged with any wealth – those few who survive entry to the Tomb generally emerge quite mad.
Most recently, the Tomb has been found as the destination of the kuo-toa raiding party which stole the Orb of the Nine Seas, and is the final destination for Jhaele’s Privateers in their Quest for the Orb.