Gelatinous Cube

Ooze · 25 hexes · SM +4 Gelatinous Cube (Enraged Eggplant; answers SRD 3.5, SRD 5.1)

A transparent cube of dense jelly, wider than the corridor it fills and nearly invisible until light catches an edge. It sweeps passages at a walking pace, digesting everything organic it engulfs and carrying the indigestible — coins, buckles, blades — suspended inside it as it goes.

Attributes

ST50

DX8

IQ0

HT12

HP147

Will0

Per10

FP12

Basic Speed1

Basic Move1

Dodge4

DR—

Melee attacks

Usage	Level	Damage	Reach
Engulf (Binding ST 30)No attack roll is necessary; the quarry may defend only by dodging and retreating. Moving through an SM+1 or smaller creature is an automatic slam. A victim who fails to dodge is pinned if smaller than the cube, or partly stuck and grappled if equal or larger. Breaking free is a Quick Contest of ST (only every 10 seconds if pinned; on a 17 or 18 the victim cannot escape unaided); the cube has +10 ST when pinning and +5 when grappling. Engulfed victims cannot breathe and begin to suffocate when out of breath. It may constrict an engulfed victim every turn at effective ST 30.	no roll	Constriction Attack, effective ST 30 (thrust 3d crushing)	C
Acid (Corrosion Aura)Always on, no attack roll. Any organic creature or object touching the cube takes 1d-1 corrosion per second; stone and metal are unaffected, which is why cubes carry undigested treasure. Engulfed creatures and objects take it as large-area injury. Selective.	no roll	1d-1 corrosion per second	C
Paralysis (Affliction 1, HT)Contact agent, always on, no attack roll. Bare skin touching the cube must roll against HT or be paralysed for 3 seconds per point of margin of failure, then stunned with a HT roll once per second to recover. Underwater the slime is diluted and victims resist at +3.	no roll	—	C

Traits (18)

• Blindness
• Doesn’t Breathe
• Doesn't Eat or Drink (Water Only)
• Doesn’t Sleep
• Early Maturation 5
• Hidebound
• High Pain Threshold
• Immunity to Metabolic Hazards
• Injury Tolerance (Homogenous, No Blood, No Eyes, No Head, No Neck)
• Invertebrate
• Invisibility (Affects Machines; Fringe)
• Mute
• No Legs (Slithers)
• No Manipulators
• Reduced Consumption 4 (Food Only)
• Slippery 5
• Unaging
• Universal Digestion

Notes

• GCS ancestry draft: gcs/gelatinous-cube.gct
• Source template total: 286 points.
• Library-rebuilt template total: 286 points.
• CER was computed from parsed Typical Stats using the Dungeons On Automatic baseline CER path.
• Review attacks, special abilities, encounter frequency, treasure, grappling, and GCS modifiers before approval.
• Size 25 hexes; Weight 50,000 lbs.

Encounter rating

CER176

Offense53

Protection123

Threat tiersevere

Appearing1

Wandering1

Tags

• srd-3-5
• srd-5-1
• ooze

GCS v5 downloads

• ↓ Character sheet (.gcs)Open directly in GCS
• ↓ Ancestry template (.gct)Apply to any character

Where this one came from

Source record

Gelatinous Cube

Source system

gurps_4e_fan_conversion / author_permission

Released under

cc_by_4_0

Conversion

0.2.0-reviewed

Review status

approved

Credit

Original GURPS conversion by Enraged Eggplant, from Monsters (May 11, 2024); adapted and republished with permission.

Description

Written by Dungeons on Automatic, released under cc_by_4_0

• GCS ancestry draft: gcs/gelatinous-cube.gct
• Source template total: 286 points.
• Library-rebuilt template total: 286 points.
• CER was computed from parsed Typical Stats using the Dungeons On Automatic baseline CER path.
• Issue #5: the automatic engulf (Binding 30, constriction at effective ST 30), the always-on corrosion aura and the contact paralysis affliction were added from the source's stated mechanics. Paralysis is a save-or-disable effect the baseline CER path does not price; see the encounter note on this record.
• CER recomputed from the reviewed Typical Stats through the canonical Dungeons on Automatic CER path: OR 53, PR 123, CER 176, threat tier severe.
• Conversion baseline reported OR -3, PR 123, CER 120 (tier severe). The reviewed values come from the consumer CER implementation, which rounds damage once after the damage-type multiplier and credits ranged accuracy; the conversion baseline ceilinged the damage base first and ignored range.
• Encounter metadata derived (solitary): average number appearing 1, wandering weight 1. Encounter metadata derived for 0.2.0 from the reviewed threat tier and creature class (appearing: minor 4 / standard 2 / major 1 / severe 1, forced to 1 for solitary classes — including swarms, which are a single multi-body creature — and raised to 6 for gregarious minor creatures; wandering weight: minor 4 / standard 3 / major 2 / severe 1). The fan-conversion source states no appearing-in-numbers or wandering values, so these are derived, not source mechanics.
• Lair, treasure, and grappling remain unpopulated in 0.2.0 by package policy: the authorized fan-conversion source states no lair, treasure, or grappling values, and review declines to invent them. See review/policy/0.2.0-empty-field-policy.md.
• Description text is original Dungeons on Automatic prose written from this record's own converted statistics and from the project's art direction for the creature. It is not derived from the authorized fan-conversion source, which states no creature descriptions, and not from any SRD. It carries its own authorship and CC BY 4.0 terms in the description field. See review/policy/description-policy.md.
• Review approved by automated-mechanical-review on 2026-07-26 (batch ee-2026-07-26-b3-cer-tails); GCS fidelity check passed, DOA playability check passed.
• CER tail record. The rating was recomputed through the consumer CER path and the tail was read against package peers in review/reports/cer-audit.md; a floor of 1 reflects a genuinely feeble creature and a severe rating tracks the record's own HP, DR and damage.