Mold, Slime

Slime Mold CR 10

This brightly-colored amoeba with pulsing veins and throbbing bladders is as big as a horse.

XP 9,600
N Large ooze
Init +8; Senses tremorsense 120 ft.; Perception +4


AC 24, touch 17, flat-footed 16 (+8 Dex, +7 natural, –1 size)
hp 126 (11d8+77)
Fort +10, Ref +11, Will +7
Defensive Abilities immune to slashing and piercing damage; DR 10/—; Immune acid, cold, death effects, mind-affecting effects, poison, ooze traits; Resist electricity 10, fire 10


Speed 30 ft., climb 30 ft.
Melee 2 slams +18 (3d6+11 plus toxin)
Space 10 ft.; Reach 10 ft.
Special Attacks combat mitosis, produce toxin


Str 32, Dex 27, Con 24, Int —, Wis 18, Cha 1
Base Atk +8; CMB +20; CMD 38 (can’t be tripped)
Skills Climb +19
SQ no breath


Combat Mitosis (Ex)

When a slime mold hits a creature and inflicts damage, it splits into two identical slime molds, each with half of the original creature’s current hit point total, rounded down. A slime mold with 10 hit points or less that splits dies instead.

Produce Toxin (Ex)

A slime mold produces a wide array of dangerous chemicals when it attacks, but the nature of these toxic chemicals varies each time it strikes a foe.

When a character takes damage from a slime mold’s slam attack, roll on the following table to determine what additional effect that particular blow’s toxic chemical has upon the target. The saving throw DCs, if any, are Constitution-based.

d6 Result
1 Creature struck takes 2d6 points of acid damage.
2 Creature struck is paralyzed for 1d4 rounds if it fails a DC 22 Fortitude save.
3 Creature struck is weakened by poison: save Fort DC 22; frequency 1/round for 6 rounds; effect 1d4 Strength; cure 2 consecutive saves.
4 Creature struck is lethally poisoned: save Fort DC 22; frequency 1/round for 6 rounds; effect 1d4 Constitution; cure 2 consecutive saves.
5 Creature struck becomes wracked with crippling pain and becomes staggered for 1d6 rounds on a failed DC 22 Fortitude save.
6 Creature struck suffers hallucinations and becomes confused for 1d4 rounds on a failed DC 22 Will save.


Environment any
Organization solitary, pair, or swarm (3–6)
Treasure incidental

Slime molds are naturally occurring organisms rarely larger than a few dozen centimeters in size. However, a few touched by cosmic energy become far larger creatures that spread slowly between star systems via spores that travel through space. They are sometimes brought to other worlds by the mi-go or other starfaring entities.

Slime molds can be controlled via bio-mechanical devices or druidic rituals, which make them potentially useful. Their preferred habitat is oxygen-free frozen worlds, but the adaptable creatures can survive for prolonged periods elsewhere. Since other environments are unhealthy for slime molds, they are under constant stress when forced to inhabit such locales. They respond with heightened metabolism and determined attempts to reproduce. As a result, instead of storing energy, as soon as a slime mold absorbs food in a terrestrial setting, it begins repeatedly undergoing mitosis. This is a losing battle, and eventually the slime mold dies, having exhausted its reserves.

Like their terrestrial namesakes, slime molds are functionally vast single-celled organisms. They are often quite brightly colored. Slime molds can swell up to around 6-8 feet tall and typically weigh a ton or so.

Their fluidity allows them to easily squeeze through small cracks or ooze up walls.

Section 15: Copyright Notice

Sandy Petersen’s Cthulhu Mythos, © 2017, Petersen Games; Authors: Sandy Petersen, Arthur Petersen, Ian Starcher.

scroll to top