Bits of broken weapons, coins, and a partially digested skeleton are visible inside this quivering cube of slime.
Gelatinous Cube CR 3
Speed 15 ft.
Melee slam +2 (1d6 plus 1d6 acid)
Space 10 ft.; Reach 5 ft.
Special Attacks engulf, paralysis
Str 10, Dex 1, Con 26, Int —, Wis 1, Cha 1
Base Atk +3; CMB +4; CMD 9 (can’t be tripped)
A gelatinous cube’s acid does not harm metal or stone.
Although it moves slowly, a gelatinous cube can simply engulf Large or smaller creatures in its path as a standard action. It cannot make a slam attack during a round in which it engulfs. The gelatinous cube merely has to move over the opponents, affecting as many as it can cover. Opponents can make attacks of opportunity against the cube, but if they do so they are not entitled to a saving throw. Those who do not attempt attacks of opportunity can attempt a DC 12 Reflex save to avoid being engulfed—on a success, they are pushed back or aside (opponent’s choice) as the cube moves forward. Engulfed creatures are subject to the cube’s paralysis and acid, gain the pinned condition, are in danger of suffocating, and are trapped within its body until they are no longer pinned. The save DC is Strength-based.
A gelatinous cube secretes an anesthetizing slime. A target hit by a cube’s melee or engulf attack must succeed on a DC 20 Fortitude save or be paralyzed for 3d6 rounds. The cube can automatically engulf a paralyzed opponent. The save DC is Constitution-based.
Due to its lack of coloration, a gelatinous cube is difficult to discern. A DC 15 Perception check is required to notice a motionless gelatinous cube. Any creature that fails to notice a gelatinous cube and walks into it is automatically engulfed.
Environment any underground
One of the dungeon’s most unusual and specialized predators, gelatinous cubes spend their existence mindlessly roaming dungeon halls and dark caverns, swallowing up organic material such as plants, refuse, carrion, and even living creatures. Materials the cube cannot digest, such as metal and stone, can eventually fill up the creature’s mass with such detritus, and at times the creature may excrete some of this material out of its body. Often the treasure and possessions of past victims remain inside the gelatinous cube, leaving a ghostly impression of their material remains.
Sages believe these creatures evolved as a specialized advancement of gray oozes. Some beings use gelatinous cubes as protectors of dungeons and underground fortifications, trapping the immense creatures in massive metal crates and transporting them through either slave power or magic to their final guard posts. They make particularly efficient waste disposal mechanisms as well—a tribe that can trap a gelatinous cube in a pit or other area that it cannot climb out of can use it as a midden or even a deadly trap, depending only on the ingenuity of the creatures who caught it.
Gelatinous cubes are generally 10 feet to a side and weigh upward of 15,000 pounds, though subterranean explorers report larger specimens trawling the deepest caves and corridors. In locations with plentiful sources of food, gelatinous cubes can exist for hundreds of years, if not thousands. However, if denied organic material for more than 6 months, a gelatinous cube begins shrinking. Eventually this stresses its walls and the creature leaks rapidly evaporating slimy liquid until its body collapses and disappears completely.