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A gelatinous cube, also known as an athcoid,[6] was a transparent ooze composed of mindless, gelatinous matter in the shape of a cube or rhombohedron.[2][6] They were especially favored by the drow god Ghaunadaur.[7]

The dungeon's floors were spotless. That should have been our first clue.
  — Jaster Hollowquill, on his exploration of Undermountain.[2]


Typically, a gelatinous cube measured between 10​ to ​15 feet (3​ to ​4.6 meters) on a side and weighed as much as 50,000 pounds (23,000 kilograms),[1][4] although legends existed of much larger cubes.[4] The creature was completely transparent, with only a glint of its surface in the light to give away its position.[1][5] The occasional random object floating in a well fed gelatinous cube's body could also serve as a warning of its presence to dungeon delvers.[2]

Gelatinous cube bodies were remarkably moldable. They could flow around objects and through narrow passages, quickly returning to their shapes once enough space was available.[6]


A gelatinous cube was a mindless predator that silently roamed ancient crypts and vaults in regular, predictable patterns.[2] As they traveled the halls of old ruins, they absorbed any material in their paths from the floors and walls.[3] Although incapable of climbing walls, particularly large gelatinous cubes could also absorb mold and moss from ceilings.[1] Organic material was quickly dissolved in the acidic ooze that made up the cube's body, while bones and inorganic matter spent some time floating within the creature until eventually expelled.[5][2][6] As they slid through the corridors, they left behind a perfectly clean path,[2] except for an occasional slimy trail.[1]



Gelatinous cubes could not see or hear, but were capable of sensing vibrations and were attracted to warmth.[6]

Gelatinous cube attack-5e

A gelatinous cube engulfs an adventurer.


When touching a creature, gelatinous cubes secreted a gummy paralyzing substance that was immediately absorbed through the skin into the victim's bloodstream. After successfully engulfing a victim, the cube moved pockets of an acidic digestive substance towards the victim's body, quickly digesting it.[6][2][5] Survivors of gelatinous cube attacks displayed scars that resembled partially melted wax.[6]

Despite being extremely effective against flesh and cellulose, this digestive fluid had no effect on inorganic matter or bones.[6][2][5] Inorganic matter would remain within their bodies for several weeks until eventually being cast out.[5]


Gelatinous cubes reproduced asexually by either dividing themselves into two smaller cubes of equal sizes[6] or via budding. In the second case, a smaller, rubbery cube was excreted into a side corridor or on a pile of refuse, and left to fend for itself until it grew into a full-sized cube. These smaller cubes were not cared for and ran the risk of being absorbed by their own parents on their next trip down the corridor.[1] Surviving young cubes then rapidly grew to adult sizes.[6]

When two gelatinous cubes met, they could temporarily fuse into a larger form that acted like a single creature. They could remain in that fused form for up to a few days before splitting and going their separate ways.[6]


Despite their sizes and homogeneous composition, gelatinous cubes were vulnerable to most usual forms of attack,[2][5] although reports existed of cubes that were immune to electricity.[1] Mind-altering effects were useless against the mindless creatures.[2][4][5] Some were said to be slowed down by cold-based spells.[5]


Despite their slow speed, gelatinous cubes were strong and could easily push back and knock over even large creatures.[4]

When facing an opponent, a gelatinous cube could slam it with an acidic pseudopod or attempt to engulf it.[2] It was possible, although difficult, for sufficiently strong creatures to escape engulfment by a gelatinous cube.[4]


According to the Demonomicon of Iggwilv, gelatinous cubes and other oozes were either fragments or the spawn of Juiblex. While this claim was not widely believed, the demon lord could exert control over them, imbuing them with a sense of purpose and even intelligence.[8]

The Imperial Zoo of Amn successfully kept a gelatinous cube in captivity for about 12 years in the mid‒14th century DR.[6]

The adventurer Haptooth claimed to have developed an oral antidote against the gelatinous cube's paralyzing secretion after years exploring Undermountain.[6]

The Waterdhavian dungeon complex of Undermountain contained numerous gelatinous cubes.[9] In the late 15th century DR, the wizard Halaster Blackcloak, while experimenting with the duergar ability to enlarge their bodies, created a giant gelatinous cube that measured 30 feet (9.1 meters) on a side.[10]



Gelatinous cubes were omnivorous[1] scavengers.[5]


These creatures were typically found inhabiting underground locations or dungeons.[4][1]They were more common in heavily frequented dungeons, due to the more readily available food and carrion.[1][4][5]


Some creatures considered gelatinous cubes to be ideal means of cleaning out their dungeon lairs of all manner of organisms. Some tried to cultivate larger cubes in order to ensure that they could reach mosses or similar organisms that collected on ceilings.[5]

Notable Gelatinous CubesEdit



Curse of the Azure BondsDungeon #30, "...And a Dozen Eggs"Hellgate KeepOut of the AbyssExpedition to UndermountainWaterdeep: Dungeon of the Mad Mage
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External LinksEdit


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Doug Stewart (June 1993). Monstrous Manual. (TSR, Inc), pp. 278–279. ISBN 1-5607-6619-0.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 Wizards RPG Team (2014). Monster Manual 5th edition. (Wizards of the Coast), pp. 241–242. ISBN 978-0786965614.
  3. 3.0 3.1 Mike Mearls, Stephen Schubert, James Wyatt (June 2008). Monster Manual 4th edition. (Wizards of the Coast), p. 202. ISBN 978-0-7869-4852-9.
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 Skip Williams, Jonathan Tweet, Monte Cook (July 2003). Monster Manual v.3.5. (Wizards of the Coast), pp. 201–202. ISBN 0-7869-2893-X.
  5. 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 5.13 Gary Gygax (December 1977). Monster Manual, 1st edition. (TSR, Inc), p. 43. ISBN 0-9356-9600-8.
  6. 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 6.12 Ed Greenwood (August 1987). “The Ecology of the Gelatinous Cube”. In Roger E. Moore ed. Dragon #124 (TSR, Inc.), pp. 56–57.
  7. Sean K. Reynolds (2002-05-04). Deity Do's and Don'ts (Zipped PDF). Wizards of the Coast. p. 11. Archived from the original on 2016-11-01. Retrieved on 2018-09-08.
  8. Wizards RPG Team (2014). Monster Manual 5th edition. (Wizards of the Coast), p. 240. ISBN 978-0786965614.
  9. Eric L. Boyd, Ed Greenwood, Christopher Lindsay, Sean K. Reynolds (June 2007). Expedition to Undermountain. (Wizards of the Coast), pp. 143, 148. ISBN 978-0-7869-4157-5.
  10. Christopher Perkins (November 2018). Waterdeep: Dungeon of the Mad Mage. Edited by Jeremy Crawford. (Wizards of the Coast), p. 34. ISBN 978-0-7869-6626-4.
  11. Christopher Perkins, Adam Lee, Richard Whitters (September 1, 2015). Out of the Abyss. Edited by Jeremy Crawford. (Wizards of the Coast), p. 35. ISBN 978-0-7869-6581-6.


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