Gelatinous Cube

Source: Monster Manual p. 242, Eberron: Rising from the Last War. Available in the SRD

Gelatinous cubes scour dungeon passages in silent, predictable patterns, leaving perfectly clean paths in their wake. They consume living tissue while leaving bones and other materials undissolved.

A gelatinous cube is all but transparent, making it hard to spot until it attacks. A cube that is well fed can be easier to spot, since its victims’ bones, coins, and other objects can be seen suspended inside the creature.

A quote from From the journal of Jaster Hollowquill, on his first exploration of Undermountain

The dungeon’s floors were spotless. That should have been our first clue.

"name": "Gelatinous Cube"
"size": "Large"
"type": "ooze"
"alignment": "Unaligned"
"ac": !!int "6"
"hp": !!int "84"
"hit_dice": "8d10 + 40"
"modifier": !!int "-4"
"stats":
  - !!int "14"
  - !!int "3"
  - !!int "20"
  - !!int "1"
  - !!int "6"
  - !!int "1"
"speed": "15 ft."
"condition_immunities": "blinded, charmed, deafened, exhaustion, frightened, prone"
"senses": "blindsight 60 ft. (blind beyond this radius), passive Perception 8"
"languages": ""
"cr": "2"
"traits":
  - "desc": "The cube takes up its entire space. Other creatures can enter the space,\
      \ but a creature that does so is subjected to the cube's Engulf and has disadvantage\
      \ on the saving throw.\n\nCreatures inside the cube can be seen but have total\
      \ cover.\n\nA creature within 5 feet of the cube can take an action to pull\
      \ a creature or object out of the cube. Doing so requires a successful DC 12\
      \ Strength check, and the creature making the attempt takes 10 (3d6) acid damage.\n\
      \nThe cube can hold only one Large creature or up to four Medium or smaller\
      \ creatures inside it at a time."
    "name": "Ooze Cube"
  - "desc": "Even when the cube is in plain sight, it takes a successful DC 15 Wisdom\
      \ (Perception) check to spot a cube that has neither moved nor attacked. A creature\
      \ that tries to enter the cube's space while unaware of the cube is surprised\
      \ by the cube."
    "name": "Transparent"
"actions":
  - "desc": "*Melee Weapon Attack:* +4 to hit, reach 5 ft., one creature. *Hit:* 10\
      \ (3d6) acid damage."
    "name": "Pseudopod"
  - "desc": "The cube moves up to its speed. While doing so, it can enter Large or\
      \ smaller creatures' spaces. Whenever the cube enters a creature's space, the\
      \ creature must make a DC 12 Dexterity saving throw.\n\nOn a successful save,\
      \ the creature can choose to be pushed 5 feet back or to the side of the cube.\
      \ A creature that chooses not to be pushed suffers the consequences of a failed\
      \ saving throw.\n\nOn a failed save, the cube enters the creature's space, and\
      \ the creature takes 10 (3d6) acid damage and is engulfed. The engulfed creature\
      \ can't breathe, is restrained, and takes 21 (6d6) acid damage at the start\
      \ of each of the cube's turns. When the cube moves, the engulfed creature moves\
      \ with it.\n\nAn engulfed creature can try to escape by taking an action to\
      \ make a DC 12 Strength check. On a success, the creature escapes and enters\
      \ a space of its choice within 5 feet of the cube."
    "name": "Engulf"
"source":
  - "MM"
  - "ERLW"
"image": "/3-Mechanics/CLI/bestiary/ooze/token/gelatinous-cube.webp"

Environment

underdark