Tarterus Tarterus , also known as Carceri , was an Outer Plane in the Great Wheel cosmology model representing alignments between chaotic evil and neutral evil . Situated between Hades and the Abyss , Tarterus was a plane of contention between the warring demon s and daemon s but few of those interlopers would challenge the native demodand s . The Companions of the Hall entered Tarterus by means of the Taros Hoop in " The Halfling ' s Gem " . Description . The six layers of Tarterus had a seemingly infinite number of worlds arranged like a string of pearls stretching into the air - filled void . In the top layer , Othrys , each orb was about the size of a Prime Material world and averaged about a hundred miles ( 160 km ) apart . In each successive lower layer the planetoids grew smaller and farther apart . There was no sun but the soil of each orb gave off heat and a dull reddish glow , similar to the phosphorescence of fire beetle s . The planets did not rotate and there was no day or night unless a greater deity wished it so in their realm . Seasons and weather occurred randomly and what little plant life there was would rapidly mature after rainfall and then wither hours later . The barriers between layers were always located at the deepest points on each planetoid and always lead to the same sphere in the next layer , so the worlds of Tarterus can be imagined as spheres nested like and each layer contained a string of orbs of a particular size . Othrys . The first layer of Tarterus was named for Mount Othrys ( from Greek mythology ) which was really two mountains on two adjacent orbs ( both also called Othrys ) each about fifty miles ( 80 km ) high joined together at the peaks in a massive citadel . The worlds of Othrys were so close together that a traveler could easily fly from one to the next . For those who did not wish to fly , the river Styx flowed through all the worlds of this level in the usual mystical fashion . Many other rivers fed the Styx , and the surfaces of this layer were mostly marsh , bogs , and quicksand . Othrys was the brightest ( due to the proximity of equal - sized worlds on either side ) and warmest layer ; no worse than a hot summer day on the Prime Material Plane . Other than the mountains , the ground was soft , like peat , and cut by deep chasms . Othrys could be reached via the Astral Plane and had portals to the Abyss , Hades , and Concordant Opposition . Long ago it could be reached via Mount Olympus , but when the Olympian gods overthrew the titans they used their combined might to shatter the part of the mountain that connected to Tarterus , thus trapping the titans on this plane . Cathrys . The planets of the second layer were smaller that those of Othrys and about five hundred miles ( 800 km ) apart . Plant life in this layer was both abundant and deadly . The flora in the overgrown jungles and grasslands secreted acid that could eat through metal in a minute or less . Minethys . The third layer of Tarterus had planetoids smaller than those of Cathrys which hovered about five thousand miles ( 8 , 000 km ) apart . The air between orbs was torn by harsh winds which carried poisonous dust storms from world to world , making most surfaces a barren desert . Huge tornadoes periodically swept through , carrying anything in its path to distant locations or even an adjacent orb . Colothys . The worlds of the fourth layer were spiked with colossal mountains rising above deep chasms . Hundreds of miles / kilometers from base to peak , the terrain of this layer made the orbs more asymmetrical than in other layers . Adjacent orbs were five hundred thousand miles ( 800 , 000 km ) apart so they appeared to be small spiky red moons in the utterly black sky . Legions of demon s and daemon s made lairs in the canyon walls . Porphatys . Black , acidic rain and snow assailed the worlds of the fifth layer from giant black clouds that moved between them . The snow only stuck to the peaks of the mountains , melting to cover the rest of the surfaces with one to six feet ( 30 to 180 cm ) of a weak acid that did not effect metal or stone but could eat away cloth in a minute or less . All barriers between this layer and the next were under water . The orbs of Porphatys were millions of miles / kilometers apart and barely discernible even when not blocked by demonic clouds . Agathys . The smallest , coldest planetoids occupied the sixth layer and were so far apart that neighboring orbs could not be seen at all . Every surface was covered in dark ice that showed streaks of red and the air was so cold it made breathing difficult . If any layer existed beyond Agathys , the barriers would have been buried under miles / kilometers of ice . Inhabitants . The dominant race that inhabited Tarterus were the winged demodand s . Shators were the ruling nobility , typically controlling major portions of an orb . All but the most powerful daemon s and demon s would avoid them . Also found on this plane were nightmare s , achaierai , and shadow demon s , with reports of mephit s , hordling s , and vargouille .