Gelatinous Cube 5e Guide
Large Ooze, Unaligned
At a Glance
CR
2
Type
Ooze
Size
Large
Alignment
Unaligned
AC
6
HP
84 (8d10 + 40)
Speed15 ft.
Ability Scores
str
14
+2
dex
3
-4
con
20
+5
int
1
-5
wis
6
-2
cha
1
-5
Key Abilities
| Ability | Description |
|---|---|
| Transparent | Even when the cube is in plain sight, it takes a DC 15 Wisdom (Perception) check to spot a cube that hasn't moved or attacked. A creature that doesn't notice it is surprised by the cube. |
| Engulf | The cube moves into creatures' spaces. Each creature must succeed on a DC 12 Dexterity save or be engulfed. An engulfed creature takes 3d6 acid damage at the start of each of the cube's turns. |
| Pseudopod | Melee weapon attack, +4 to hit, reach 5 ft. 3d6 acid damage. |
How to Run This Monster
The gelatinous cube is a dungeon hallway cleaner. It fills a 10-foot corridor perfectly and moves slowly toward prey. Its transparency makes it a deadly ambush predator in dark dungeons. It simply rolls over creatures and dissolves them.
Encounter Ideas
Place gelatinous cubes in 10-foot-wide corridors where they fill the entire passage. Describe the corridor as unusually clean — that's the cube's trail. Scatter visible objects (coins, bones, weapons) floating inside the cube as a visual clue. Great for low-level dungeon crawls.
Loot
Whatever the cube has dissolved around — coins, weapons, armor, and other indigestible items float inside it. After killing the cube, these items can be salvaged (typically 2d10 gp in coins and 1d4 mundane items).
Common Mistakes
Common Mistake
Forgetting the cube is transparent and nearly invisible in dim dungeons
Common Mistake
Not having it fill the entire corridor width
Common Mistake
Allowing easy escape — an engulfed creature must use its action to try to escape
DM Tips
DM Tip
Use the cube as an environmental hazard during other encounters
DM Tip
Describe the 'clean' corridor as a clue before the encounter
DM Tip
Great for teaching new players about dungeon awareness
Frequently Asked Questions
Sources & Further Reading
- Gelatinous Cube — D&D 5e Wikidot — Full stat block
- Gelatinous Cube — D&D Beyond — Official monster reference
- Gelatinous Cube — Roll20 Compendium — Structured stat block