Ooze, Stonebuilder

Huge ooze, unaligned

24 (+7) 6 (-2) 20 (+5) 1 (-5) 6 (-2) 1 (-5)

Armor Class 16 (natural armor)
Hit Points 138 (12d12 + 60)
Speed 10 ft., climb 10 ft.
Skills Stealth +2
Damage Resistances cold, fire, lightning; bludgeoning, piercing, and slashing from non-magical weapons
Damage Immunities acid, thunder
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone
Senses blindsight 60 ft., passive Perception 10
Challenge 9 (5,000 XP)

Special Traits

  • Acidic Touch. The stonebuilder ooze does 5 (2d4) acid damage to any organic matter (wood, leather, living tissue) that it is in contact with at the end of its turn.
  • Camouflage. A motionless stonebuilder ooze has advantage on stealth checks.
  • Engulf. The stonebuilder ooze can occupy another creature’s space, and vice versa. A creature that starts its turn in the ooze’s space is subject to its secretion.. The ooze’s space is difficult terrain.
  • Secretion. A creature engulfed by the stonebuilder ooze, or hit by its slam attack, must succeed at a DC 16 Dexterity saving throw or become restrained for one minute. A creature that spends an action trying to remove the resin is entitled to another saving throw at the end of its turn. After 1 minute the resin hardens into stone, and requires either magic or an hour’s labor with appropriate tools to remove.


  • Multiattack. The stonebuilder ooze makes two slam attacks, plus an additional slam attack against each creature within its space.
  • Slam. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 16 (2d8 + 7) bludgeoning damage and the target is subject to Secretion.
  • Surge (recharge 5-6). The ooze raises itself up into a wave taller than a man and surges forward 20 feet.


Only found outside its lair at night, the stonebuilder ooze invariably tries to Engulf and Slam opponents, and will fight to the death, not recognizing when it is outmatched.


This enormous ooze, twenty feet or more in diameter, has a dull, pebbled surface, strongly resembling local rock and sand. It flows with a curious rippling motion, occasionally rising into great waves.

Stone builders secrete an acidic resin that they combine with dust and sand to create a sturdy stone-like material, which the ooze builds up into a rough cone, pocked with entrance tunnels. In the heat of the day, the ooze takes shelter from the sun inside its stoney home, and at night it emerges to hunt.

This One is Just Right. The stonebuilder’s conical homes are as strong as solid stone, 20 or more feet wide and high, and have walls 2 to 3 feet thick. The cones are a marvel of engineering, for they remain cool even under the hot desert sun. They are consequently prized as housing by creatures that are able to seize them from their oozy creators. But woe to the intruder still inside when its owner returns!

Section 15: Copyright Notice

Creature Collection 5e Copyright 2020 Onyx Path Publishing, Inc.