Sepio Pristis Fossor 404 – GearAscendancy.com

Original Life Forms

Class Amphibia: Hairy Frog (Trichobatrachusrobustus)
Class Arachnida: Trapdoor Spider (Family Idiopidae)
Class Chondrichthyes: Largetooth Sawfish (Pristispristis)
Class Cephalopoda: Common Cuttlefish (Sepiaofficinalis)

Appearance The Sepio-Pristis Fossor is a low-slung, wide-bodied horror adapted for a life of ambush and excavation. Its body is a powerful fusion of amphibian and arachnid, possessing eight limbs. The front two are muscular digging arms, the middle four are stout, spider-like walking legs, and the rear two are oversized, frog-like legs coiled for explosive leaps. The creature’s skin is rubbery and scaleless, covered in a fine coat of hair-like filaments that constantly shift and ripple. This entire surface is a single, complex organ of chromatophores, allowing it to project complex, shifting patterns, hypnotic strobing lights, or a perfect, seamless camouflage that matches its environment with impossible fidelity.

Its head is broad and flattened, dominated by two large, intelligent cuttlefish eyes with distinctive W-shaped pupils. Instead of a mouth, a formidable, bone-white rostrum extends from its face—a long, flat saw lined with sharp, irregular denticles, which it uses as both a weapon and a digging tool. When submerged, it breathes through a set of pulsating gills on the sides of its thick neck. The tips of its six forward-most appendages conceal a gruesome weapon: by intentionally fracturing its own phalanges, the creature can force sharpened bone shards through pads in its digits, creating retractable claws. From its abdomen, it can produce thick strands of silk, which it uses to construct its traps.

Size This is a heavy, dense creature built for power, not height. An adult stands only about 4 feet tall at its shoulders but can be up to 8 feet wide across its leg span. From the tip of its saw to its rear, it measures between 12 and 15 feet long. Its weight is considerable, averaging between 1,500 and 2,000 pounds due to its dense bone structure and musculature.

Speed On land, the Fossor’s movement is a deliberate, powerful waddle. It is not designed for pursuit. However, its powerful hind legs allow it to make prodigious leaps of up to 40 feet to surprise prey or escape a threat. It is a surprisingly fast and agile swimmer, using its powerful limbs and undulating body to propel itself through water. Its greatest speed is in excavation, where it can tunnel through mud and packed earth with terrifying efficiency.

Stat Modifiers

Strength: Very High
Dexterity: Low
Constitution: Very High
Intelligence: Moderate (Cunning)
Wisdom: Moderate
Charisma: Very Low

Skills

Stealth: Its combination of natural camouflage and burrowing habits makes it a master of stealth. It is exceptionally difficult to detect when prepared for an ambush.
Athletics: It is a powerful jumper and swimmer, capable of surprising bursts of movement in its chosen environment.
Trapping: The creature is a natural engineer of deadfalls. It uses its silk, knowledge of soil composition, and strength to create large, perfectly concealed pit traps.
Intimidation: Its hypnotic light displays can disorient and frighten prey, and its general appearance is monstrous.

Behavior This creature is the ultimate territorial ambush predator. It does not actively hunt or stalk; it meticulously prepares its hunting grounds. The Fossor excavates a large, complex burrow near a body of water, often with multiple chambers and a primary entrance hidden underwater. The area above its den becomes a death zone. It uses its saw and powerful arms to dig, creating thin-roofed chambers just below the surface. It then constructs a “trapdoor” over each cavity using silk mixed with local soil and vegetation, making it indistinguishable from the surrounding ground.

The Sepio-Pristis Fossor will lie in wait for days on end in a chamber beneath one of its traps, sensing vibrations through the earth. When a creature of sufficient weight steps on the trap, it collapses, dropping the victim into the waiting predator’s clutches. If prey spots it from a distance, it will use its skin to produce a mesmerizing, pulsating light show to confuse and lure it closer. Its saw is used for defense and for dismembering prey for easier transport to its underwater larder.

Diet The Sepio-Pristis Fossor is a carnivore that will eat anything it can catch. Its diet consists of herd animals coming to drink, large reptiles, other swamp predators, and any avatars unfortunate enough to wander through its territory. Prey is often disabled by the fall and then immediately attacked. It will then drag the carcass deeper into its burrow, frequently to an underwater cache where the meat is left to soften.

Emotions This creature operates on a cold, patient, and predatory instinct. It exhibits no emotions in the traditional sense, only states of being: a patient, nearly meditative waiting state, a focused and explosive state of attack, and a frenzied, defensive rage if its burrow is breached. Its hypnotic light displays are not an expression of emotion but a calculated predatory tool.

Environment Where Found It is exclusively found in warm, wet regions on the world of Saṃsaˉra. It prefers the muddy banks of slow-moving rivers, murky lakes, and mangrove swamps. Its territory can be identified by an eerie lack of other large animal life and the presence of numerous, suspiciously perfect patches of ground that feel unnaturally soft underfoot.

Tags Feral, Creature, Carnivore, Ambush Predator, Burrower, Trap-Setter, Amphibious, Camouflage, Hypnotic, Regenerative (for its bone claws), Subterranean, Territorial, Vibration Sense, Patient Hunter, Silk Spinner, Bio-luminescence, Bone Claws, Saw-Nosed

Age This creature possesses a remarkably long lifespan, a trait developed from its patient, low-energy hunting style. An individual can live for 150 to 200 years, growing larger and more cunning with each passing decade.

Egg Sac: Life begins within a large, silken egg sac containing several hundred eggs. The sac is anchored in an underwater chamber within the parent’s burrow and is fiercely guarded.
Larval Stage: The young hatch into gilled, carnivorous tadpoles that swarm in the flooded portions of the lair, feeding on subterranean insects and, predominantly, each other. During this stage, which lasts about a year, their signature rostrum is only a soft, cartilaginous nub.
Juvenile Stage: The larvae that survive develop limbs and rudimentary lungs, allowing them to crawl throughout the burrow network. They instinctively begin to dig and spin silk, practicing the skills they will need to survive. Cannibalism continues to whittle down their numbers until only a handful of the strongest and most cunning juveniles remain.
Sub-adult: After nearly a decade of development within the safety of the parent’s lair, the 3- to 4-foot-long sub-adults are violently driven out to fend for themselves. This is the most perilous time in their lives, as they must wander to find unclaimed territory and excavate their own first burrow, all while avoiding other predators.
Adult: At around 30 years of age, the creature reaches its full size and reproductive maturity. It will have established a formidable burrow and will spend the next century and a half maintaining its trap-laden territory.
Ancient: An individual over 150 years of age is considered an Ancient. Its rostrum may be scarred and chipped, but its wisdom and the sheer scale of its labyrinthine burrow system make it far more dangerous than a younger adult.

Mating Reproduction is a rare and perilous event, undertaken only a few times in a Fossor’s long life. When a female is receptive, she releases a complex pheromone into the waterways of her territory. A wandering male, having abandoned his own burrow in a once-in-a-lifetime search, may sense the trail. The courtship is a test of skill, not combat. The male must prove his worth by contributing to the female’s burrow, excavating a new chamber or constructing a new, masterfully designed trapdoor system under her watchful eye. If his work is satisfactory, she will accept him. If his efforts are clumsy or his build is weak, she is likely to attack and consume him. After mating occurs deep within the burrow, the male departs forever, leaving the female to lay and guard the egg sac alone.

Tactics The Fossor’s tactics are predicated on complete battlefield control and avoiding a fair fight at all costs.

Territory Preparation: The creature’s primary tactic is its lair. It spends years engineering a landscape of death, riddling the ground with deep pits covered by perfectly camouflaged trapdoors made of silk and earth.
Luring and Waiting: Lying in wait beneath a trap, it senses the vibrations of approaching prey. It may employ its bio-luminescent skin to create subtle, hypnotic light patterns visible through the thin layer of soil, piquing the curiosity of prey and drawing them onto the trap’s center.
The Ambush: The attack begins when the trap gives way, plunging the victim into a dark, confined pit with the waiting predator. The fall itself often injures and disorients the target. The Fossor attacks instantly, using its saw-like rostrum in the tight quarters to dismember and neutralize the prey before it can recover.
Open Combat: If forced to fight outside its burrow, its tactics shift to aggressive defense. It uses its long rostrum in wide, sweeping arcs to control space and keep enemies at a distance. For closer threats, it unleashes a flurry of attacks with its retractable bone claws. Its powerful legs are used not for pursuit, but for explosive leaps to reposition, crash down upon an enemy, or escape to the safety of deep water or its burrow entrance.

Actions

Saw Sweep: A powerful melee attack that strikes all targets in a 15-foot arc in front of the creature.
Flurry of Claws: The creature makes multiple, rapid strikes against a single target with its retractable bone claws. These attacks are fast and can inflict deep, bleeding wounds.
Crushing Leap: The creature can jump onto a target up to 40 feet away. The target must make a saving throw or be knocked prone and pinned beneath the creature’s immense weight.
Hypnotic Display (Limited Use): The creature causes its entire body to pulse with a disorienting, strobing display of colored light. All who can see it must make a Willpower save or be dazed and unable to act for a short duration.
Subterranean Evasion: When in water or on soft earth, the creature can use an action to burrow out of sight, disappearing completely. It can re-emerge anywhere within 30 feet on a subsequent turn.
Lair Action (Trap Collapse): When fighting within its prepared territory, the creature can stomp a powerful limb on the ground, causing a nearby trapdoor to collapse and creating a hazardous pit.

Other Interesting Information

Ecological Role: The Sepio-Pristis Fossor is a keystone species and a powerful ecosystem engineer. Its predation prevents the overpopulation of large herbivores and other predators along waterways. Over centuries, its abandoned, collapsed burrows create new ponds and wetland habitats, shaping the very landscape it lives in.
Magical Properties: The creature’s camouflage and hypnotic displays are passive manifestations of illusion magic inherent to its being, a trait magnified from its cephalopod ancestry by the magical nature of Saṃsaˉra. The light display is known to disrupt concentration, making it difficult for magic-users to accurately target the creature.
Harvestable Materials:
- Pristis Rostrum: The saw-like nose is an incredibly valuable trophy. It can be masterfully worked into a greatsword or polearm that excels at tearing through armor.
- Chroma-Hide: The creature’s skin is one of the most difficult materials to tan, but if successful, it creates a magical leather that grants the wearer a limited ability to camouflage themselves.
- Cuttle-Lens: The large, W-shaped crystalline lens of the eye is a vital component for powerful scrying devices and artifacts designed to see through magical illusions.
- Fossor Silk: The silk produced for its traps is lightweight, waterproof, and stronger than steel cable. It is sought after for creating inescapable nets, bindings, and even for reinforcing structural components in airships.

An adventuring party would face the Sepio-Pristis Fossor 404 either as the deliberate target of a high-stakes hunt or as the terrifying, unforeseen obstacle in an unrelated mission. The creature’s reclusive, stationary nature means encounters are rarely a matter of chance, but a consequence of trespassing on its meticulously prepared territory.

Reasons for Searching

To deliberately seek out a Sepio-Pristis Fossor is to undertake a mission of extreme peril, typically motivated by the promise of unique rewards that cannot be obtained by any other means. Patrons who commission such hunts are often desperate, vastly wealthy, or have goals that transcend mere monster-slaying.

Engineering and Construction Contracts: A guild of engineers building a critical bridge over a wide gorge or laying the foundations for a new floating city pylon may find that conventional materials lack the required tensile strength and resilience to water damage. They would post a substantial contract for the acquisition of Fossor Silk. The mission would not be to simply kill the beast, but to perform a dangerous live harvest of the silk glands or to capture the creature so its silk can be farmed—an endeavor requiring a party of exceptional skill in trapping and subdual, not just brute force.
Acquisition of a Truth-Seeing Artifact: In a world of political intrigue where illusion magic and shapeshifters can influence the powerful, a high-ranking spymaster, inquisitor, or noble may seek an absolute countermeasure. The Cuttle-Lens from the creature’s eye is fabled to be the core component in artifacts that can perceive magical deception. A party would be hired for a clandestine and dangerous mission to hunt the creature in a remote, specified location and retrieve the eye, with the reward being immense wealth or a powerful political favor.
The Quest for a Panacea: A new and virulent plague might sweep through a population center, causing a bizarre magical ailment for which there is no known cure. A reclusive alchemist or healer might discover a potential cure in their research but require a key, seemingly unobtainable ingredient: the powdered Bone Claw Shards of a Sepio-Pristis Fossor, which contain a unique biological agent that promotes miraculous regeneration of bone and tissue. This would trigger a desperate, time-sensitive quest where the party must venture into the swamplands and face the horror to save a city or a single, important individual.
Forging a Legendary Weapon: A famous blademaster, a reigning champion of the gladiatorial arena, or a wealthy collector might issue a grand challenge with a legendary reward: they seek to commission a weapon made from the Pristis Rostrum of an ancient specimen. The saw of a fully-grown Fossor is said to be harder than steel and naturally serrated to tear through armor. This would initiate a pure trophy hunt for the largest and most dangerous Fossor the party can find, a quest that would likely attract rival adventurers seeking the same glory and reward.

Reasons for Encountering

Accidental encounters are a result of a party unknowingly entering the creature’s prepared hunting grounds. These situations often begin not with a roar, but with a silent, terrifying discovery that the very ground beneath their feet is a weapon.

Investigating a Vanishing Point: A section of a vital riverside trade route becomes known as the “Vanishing Point.” Entire caravans, steam-wagons, and their crews disappear overnight without a trace—no wreckage, no bodies, no signs of a struggle. The party is hired to investigate what is assumed to be the work of sophisticated bandits or a new type of flying beast. As they patrol the eerie, silent route, they will find no clues until a horse, a companion, or a section of the road itself suddenly gives way, dropping into a dark pit from which a horrific chittering can be heard. The mission instantly shifts from investigation to a desperate subterranean rescue.
Surveying Unsettled Land: In a world of expanding populations, a guild or governing body might hire a party to survey a tract of “pristine” riverside land for a new settlement or industrial complex. The area appears perfect—flat, fertile, and strangely devoid of any dangerous predators. As the party conducts its survey, they may note the unsettling silence and the unnatural softness of the ground in certain circular patches. Their presence and the noise of their work would eventually provoke the lair’s owner. The encounter would not be a simple fight, but a tactical nightmare as the Fossor uses its network of traps to separate the party, collapsing the earth to isolate and destroy them one by one.
Exploring a Newly Revealed Ruin: Following a season of intense, magically-influenced floods, a river changes its course, eroding a cliffside to reveal the entrance to what appears to be a lost tomb or ancient structure. Drawn by the lure of discovery and treasure, the party ventures inside. They soon discover that the “ruin” is not made of stone, but of hardened earth and silk, and that they have not found a tomb, but have instead wandered into the exposed upper levels of an ancient Fossor’s burrow. Enraged by the violation and the damage to its home, the creature would use the flooded, narrow tunnels to its advantage, striking from the murky water like a true monster of the deep before disappearing back into the labyrinth.

In addition to the most obvious and valuable parts of the Sepio-Pristis Fossor 404, nearly every organ and biological system within the creature can be harvested for a specific purpose, making its corpse a treasure trove for knowledgeable artisans, alchemists, and engineers.

Hypnotic Ink Sac Inherited from its cephalopod ancestor, the Fossor possesses a large ink sac, but its contents are far more potent than simple pigment. The thick, oily, iridescent fluid, known as Hypnotic Ink, is suffused with the same psychoactive, bio-luminescent properties as its skin. When deployed in water, it creates a billowing cloud of mesmerizing, shifting patterns that actively disorient and confuse pursuers. When harvested, this ink is a priceless commodity for illusionists and spies. It can be used as a component in smoke pellets or flash bombs that cause temporary blindness and bewilderment. As a literal ink, it is used to scribe scrolls of concealment or confusion; the words themselves seem to wriggle and shift, making them readable only to those with the proper mental discipline or a specific magical key.

Paralytic Venom Glands To subdue prey that survives the fall into its trap without a prolonged struggle, the Fossor utilizes a potent neurotoxin from glands located near its rostrum, a trait from its arachnid heritage. This Paralytic Venom is not typically lethal on its own but induces rapid, temporary paralysis. The harvested venom is a double-edged sword, sought by both healers and assassins. In its raw form, it is a discreet and effective tool for incapacitating a target. When carefully diluted and processed by an alchemist, it becomes a powerful anesthetic, allowing for complex magical surgery. It is also the primary ingredient in potions that grant the user the ability to feign death or enter a short-term state of suspended animation.

Filter-Gills The creature’s large, feathery gills are a marvel of biological engineering, capable of extracting oxygen from even the most stagnant, murky water. These Filter-Gills are lined with a complex web of magically-attuned membranes that also filter out toxins and impurities. When dried and cured, sections of these gills are used by alchemists as the ultimate purification medium, capable of cleansing a potion of a magical taint or removing a subtle poison. In the great underwater cities or on trans-oceanic ships, larger, intact gill structures are incorporated into industrial-scale water filtration systems, providing clean, drinkable water from almost any source.

Vibratory Dermal Filaments The fine, hair-like filaments covering the creature’s skin are not hair but highly sensitive dermal papillae that allow it to feel minute vibrations in the water and earth. When carefully shaved from the hide and spun into a thread, these Vibratory Filaments retain their sensitivity. This thread can be woven into the palms of gloves or the soles of boots, granting the wearer an enhanced sense of touch, allowing them to detect the shifting tumblers of a lock, the subtle vibrations of an approaching creature through the floor, or the instability of a rock face before a collapse.

Triple-Cycle Hearts A biological quirk from its cephalopod lineage, the Fossor possesses three hearts that beat in a complex, synchronized rhythm to pump its heavy blood. These Triple-Cycle Hearts, if preserved using chrono-mantic enchantments immediately after the creature’s death, continue to pulse in unison. Enchanters prize them as biological regulators or capacitors for complex magical items. A heart might be integrated into a wand that allows it to store three charges instead of one, or used as the core of a defensive amulet that releases three pulses of protective energy in rapid succession before needing to “re-synchronize.”

All-Consuming Digestive Enzymes The creature’s stomach contains a powerful cocktail of enzymes capable of breaking down nearly any organic material, including bone, chitin, and dense wood. These All-Consuming Enzymes, once extracted and stored in magically reinforced glass vials, serve as a universal solvent. Crafters use it to strip away unwanted material or to soften incredibly hard woods for carving. In large cities, a diluted form is used as the most effective, albeit dangerous, drain and sewer cleaner available. It is also rumored to be used by criminal syndicates as a discreet method for disposing of bodies.

Serrated Rostrum Denticles While the entire saw-like rostrum is a prize, the individual tooth-like Serrated Denticles that line its edge are valuable in their own right. They are composed of a unique, self-sharpening biological composite. Skilled fletchers use them as arrowheads and crossbow bolt tips that cause grievous wounds that are difficult to heal. A bladesmith can painstakingly embed a row of these denticles along the edge of a sword, creating a serrated weapon that never loses its edge and can saw through armor and shields.

Twins and Ground That Eats

This is the telling of Yarrow-Who-Walks and Willow-Who-Swims, the two who were one, from the time when the world of Saṃsaˉra was green and its history was not yet written in stone. Their village was born of the river, and their people lived with the water’s blessing. But then the blessing soured. The river grew sick, and the land by the river grew hungry.

It began with the water. The current grew slow and strange, and the fish, they vanished. Then it was the land. A child chasing a butterfly near the riverbank disappeared. The ground where he stood was soft, but there was no hole. The ground would open its mouth, and a man would be gone. The people were afraid. They said a curse was on them. They called the beast that they did not see the Ground That Eats, for its hunger was the earth itself.

Yarrow, his feet knew the secrets of the soil and the language of bent twigs. Willow, her hands knew the songs of the water and the minds of the fish. They were twins, and their hearts beat as one. They saw the fear of their people and they said, this is a disharmony of land and water. It is one creature, and so we two must face it.

Yarrow walked the sick land. He did not step where the ground looked soft. He saw the circles of false earth, woven with a thread that was not of a plant. He saw the tracks of a thing with too many legs, a thing of great weight. He found a lie of solid earth, and he knew the mind of the land-trapper.

Willow swam the sick river. She felt the wrong currents that pulled toward the bank. She swam in the deep, and she found a great darkness, a hole where the river went to die. It was the entrance to a house of mud and water. She felt the vibrations of a great thing moving in the deep, and she knew the heart of the water-lurker.

They met at the river’s edge. He spoke to her of the woven traps. She spoke to him of the water-house. They said to each other with one voice: We cannot go into its house. The ground is its shield and the water is its cloak. It must come out of its house.

So they made a plan. They would not fight the trap; they would make the trapper leave his trap. They found the Great Stone, a finger of granite that jutted into the river, a place which had no memory of being soil. It was a place the Ground That Eats could not command.

Upon the Great Stone, Yarrow made a sound of war. He beat a dry hide drum and stomped his feet, a challenge to the master of the land. In the water below the Great Stone, Willow made a sound of prey. She thrashed with a great branch and slapped the water, a promise of a great, dying fish for the master of the river. They made a noise that the patient beast could not ignore.

The Ground That Eats came forth. Its anger was great. It rose from a hidden hole at the base of the Great Stone, a horror of two worlds. Its eight legs carried it onto the rock, and its skin was a shifting lie of color. Its face was a bone-saw, and its hands were broken to make knives. It crawled toward Yarrow, and on its skin began the star-sickness, a light that made the eyes forget how to see.

But as it focused on the man of the land, the woman of the water rose from the river behind it. Willow was there, with a fisherman’s harpoon of sharpened bronze. The beast was caught. It could not retreat to its water-house. It could not lure them into its earth-traps. It was alone, on the hard stone, between the two who were one.

It screeched and swung the bone-saw of its face at Yarrow. Yarrow met it with a shield of woven ironwood, and the sound was of mountains breaking. The star-sickness pulsed, but Yarrow looked at the beast’s shadow, not its skin. As the beast struck at Yarrow, Willow drove her harpoon deep into one of its thick back legs.

The beast roared and turned, a motion of impossible speed, but now it faced Willow. And Yarrow was at its back. Yarrow was the land. Willow was the water. The beast was of both, and so it was caught between. It did not know which to fight. Its great mind, made for traps and waiting, could not understand a battle on two fronts. It leaped, but its leg was injured. It slashed, but its foes were apart. Yarrow showed it a challenge to the front. Willow showed it pain from the back.

They fought until the sun was low. The Great Stone was slick with the creature’s strange blood. At last, weary and wounded, the great beast faltered. Yarrow, with a final war cry, drove his spear into the place where its neck met its body. Willow, with a final surge, cut through its wounded leg with her bronze knife. The Ground That Eats fell upon the Great Stone and was still.

And so the river was healed, and the ground was no longer hungry. The people of the village sang the names of the twins who were one.

The Moral: A monster that lives in two worlds can only be defeated by a warrior who understands both.

Suggested conversions to other systems:

Call of Cthulhu (7th Edition)

The Hypogean Deceiver This creature represents a terrifying evolutionary path utterly alien to mammalian understanding. It does not hunt; it curates a garden of death. It sculpts the very earth into a weapon, lying in silent, patient contemplation for weeks or months until its territory is violated. Its mind is a strange, cold intelligence focused solely on the geometry of its traps.

STR 130 CON 120 SIZ 130 DEX 60 INT 65 POW 90 HP: 25 Dmg. Bonus: +3d6 Build: 4 Move: 6 / 10 swimming / 4 burrowing

Attacks

Attacks per round: 1 (or may use Hypnotic Pattern)
Saw-Rostrum: 70%, damage 1d10+DB. On an Extreme success, the target is impaled, suffering an additional 1d10 damage next round as the saw thrashes.
Bone Claw Flurry: 50%, the creature makes 1d4+1 attacks, each dealing 1d6 damage. The damage bonus does not apply to these weaker, faster strikes.

Special Abilities

Pitfall Lair: The Deceiver’s territory is riddled with cunningly disguised pit traps. When moving through the area, Investigators must make a successful Spot Hidden roll at a penalty (a Hard success) or a Luck roll to avoid stepping on one. Failure results in a 20-foot fall into the creature’s subterranean lair, taking 2d6 damage and becoming separated from the group.
Hypnotic Pattern: As an action, the creature can project a mind-altering pattern of lights from its skin. All who view it must succeed on an opposed POW roll or be mesmerized, unable to act for 1d3 rounds. This is a terrifying psychic assault, not merely a visual trick.
Burrow: The creature can disappear into soft earth or mud as a full movement action.

Armor: 8-point rubbery hide and chitin. Sanity Loss: 1d4/1d10 to witness the creature’s true form emerge from the earth. Being subjected to its Hypnotic Pattern costs 1/1d6 SAN. Falling into its trap-lair costs 0/1d4 SAN.

Blades in the Dark

The Silt-Maw A horror story told by those who work the canals and forgotten under-tunnels of Doskvol. They say the ground itself has a hunger in certain places, that the mud will pull you under into a waiting mouth. The Silt-Maw is a patient monster, an architect of traps, turning its territory into a maze from which there is no escape. It doesn’t just live in the earth; it is one with it.

Threat Level: Tier V Instinct: To ensnare and consume.

Mechanics of the Silt-Maw:

Its lair is the primary threat. Moving through its territory is a group action; the result determines how many ticks are marked on the The Walls Close In clock.
Its Hypnotic Lights are a consequence of looking at it directly. The first time, a PC must Resolve or hesitate, giving the Maw an opportunity. Continued exposure may inflict Level 2 Harm “Mesmerized.”
Its Saw-Nose attack is a devastating consequence, inflicting Level 4 Harm (“Severed Limb”) or breaking equipment.
Its Bone Claws inflict Level 2 Harm (“Viciously Gouged”) and are fast enough to strike anyone who gets too close.

Clocks:

The Walls Close In (8-Clock): Ticks when the crew moves carelessly or makes loud noises. When full, a section of tunnel collapses, separating the crew or trapping them.
Dragged Below (6-Clock): A clock for an individual PC. Starts when they fall into a trap. When full, the Silt-Maw has dragged them into its underwater larder to be drowned and stored.
Lair Destabilized (10-Clock): The crew cannot hope to kill the Silt-Maw in a straight fight. They must destabilize its home by causing cave-ins, flooding tunnels, or using strange magic to drive it into the open, where it is vulnerable.

Dungeons & Dragons (5th Edition)

Subterranean Saw-Maw Huge monstrosity, unaligned

Armor Class 17 (natural armor) Hit Points 199 (19d12 + 76) Speed 20 ft., swim 40 ft., burrow 20 ft.

STR 22 (+6) DEX 10 (+0) CON 19 (+4) INT 8 (-1) WIS 14 (+2) CHA 7 (-2)

Saving Throws STR +10, CON +8 Skills Perception +6, Stealth +8 Senses darkvision 60 ft., tremorsense 120 ft., passive Perception 16 Languages — Challenge 13 (10,000 XP) Proficiency Bonus +4

Amphibious. The saw-maw can breathe air and water.

Tunneler. The saw-maw can burrow through solid rock at half its burrowing speed and leaves a 10-foot-diameter tunnel in its wake.

Lair Actions On initiative count 20 (losing initiative ties), the saw-maw can take a lair action to cause one of the following effects; it can’t use the same effect two rounds in a row:

The saw-maw causes a 10-foot-square section of floor within 120 feet of it to collapse into a 20-foot-deep pit. Any creature on that floor must succeed on a DC 15 Dexterity saving throw or fall in.
A hypnotic pulse of light emanates from a point the saw-maw can see. Each creature within 20 feet of that point must succeed on a DC 15 Wisdom saving throw or be charmed by the saw-maw until the end of its next turn.
A section of the ceiling collapses above one creature the saw-maw can see within 120 feet of it. The creature must succeed on a DC 15 Dexterity saving throw or take 10 (3d6) bludgeoning damage and be knocked prone and restrained. The creature can use an action to make a DC 15 Strength check, freeing itself on a success.

Actions Multiattack. The saw-maw makes one attack with its Saw-Nose and two attacks with its Bone Claws.

Saw-Nose. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 25 (3d12 + 6) slashing damage.

Bone Claw. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 15 (2d8 + 6) piercing damage.

Hypnotic Display (Recharge 6). The saw-maw creates a display of strobing, colored lights. Each creature within 30 feet of the saw-maw that can see the lights must succeed on a DC 15 Wisdom saving throw or be stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Knave (2nd Edition)

Trapdoor Maw A bloated, eight-legged amphibian horror that lives deep beneath swamps and riverbeds. It does not hunt, but rather engineers its entire territory into a single, comprehensive trap. The ground itself is its weapon.

HD 12 Armor 17 Morale 9 (12 if its lair is flooded or destroyed)

Qualities:

Tremorsense: The maw automatically detects the location of any creature touching the ground within its lair (a 200ft radius from its central chamber). It cannot be surprised.
Trap Lair: The maw’s lair is a deathtrap. When PCs move, the GM should secretly roll a d6. On a 1-2, they have stepped on a hidden pit trap and must save vs. Hazard to leap back. On a failure, they fall 30 feet (3d6 damage) and are separated from the party.
Valuable Corpse: Its saw-nose, heart, and silk glands are worth 4d6 x 1000s.

Actions (d6 roll on its turn):

Burrow: The maw disappears into the earth or mud. It will re-emerge on its next turn, bursting from the ground beneath a random PC, who must save vs. Hazard or be thrown prone and take 1d10 damage.
Saw-Nose Sweep: Attacks all PCs in a 10ft arc in front of it for 2d12 damage. The attack shreds shields on a hit.
Bone Claw Flurry: Makes 1d4+1 attacks against a single target for 1d8 damage each.
Hypnotic Gaze: Targets a single PC who can see it. The target must save vs. Spell or stand motionless and confused for one round.
Crushing Leap: Jumps onto a PC, who must save vs. Paralysis or be pinned. A pinned PC can only be freed if the maw is forced off by a powerful spell or if two other PCs use their actions to succeed on a contested Strength check.
Saw-Nose Sweep: Attacks all PCs in a 10ft arc in front of it for 2d12 damage. The attack shreds shields on a hit.

Fate Core System

The Weaver of Sunken Earth This creature is less a predator and more a sentient, geological event. It is an architect of hunger, shaping its entire environment into a complex weapon. It treats combat as a failure of its primary strategy: to have its enemies defeated by the world itself long before they ever lay eyes on it.

High Concept: Patient Architect of Ambush Lairs Trouble Aspect: Frenzied and Reckless When Lair is Breached

Other Aspects:

The Ground is My Skin
Hypnotic Kaleidoscope of Light
Bone-Saw Face, Bone-Shard Claws

Skills

Peak (+5): Crafts
Great (+4): Physique, Stealth
Good (+3): Fight, Athletics
Fair (+2): Notice
Average (+1): Will

Stunts

Master Trapper: Because it is a Patient Architect of Ambush Lairs, it gets a +2 when it uses Crafts to create situation aspects like Hidden Pit Trap or Unstable Ground before a conflict begins.
Hypnotic Kaleidoscope: Because it has a Hypnotic Kaleidoscope of Light, it can use Provoke to make a mental attack against all targets in a single zone. This attack inflicts mental stress as waves of awe and confusion.
Erupt From The Earth: The Weaver can use Stealth to make a physical attack, bursting from a hidden position in the ground or water. On a successful hit, in addition to damage, it attaches the situation aspect Showered in Dirt and Debris to the target with one free invocation.

Stress: Physical [1][1][1][1] Mental [1][1] Consequences: One Mild, one Moderate, one Severe.

Numenera & Cypher System

The Geomorphic Predator A creature of the Ninth World that seems to actively engineer its own habitat into a weaponized ecosystem. Its intelligence is not sapient, but structural and architectural. It thinks in terms of geology, water flow, and stress points, turning its entire territory into a single, comprehensive killing machine.

Level: 8 Motive: To create the perfect hunting ground, to ensnare prey. Environment: Anywhere with soft earth and access to water, such as riverbanks, swamps, or ancient, silt-filled ruins. Health: 24 Damage: 8 points. Armor: 2 Movement: Short; can burrow and disappear into soft earth or mud as its entire action.

Modifications:

Task difficulty to spot one of its pit traps is Level 9 (27).
Senses vibrations through the ground as a Level 9 perception task.

Combat:

The Predator’s primary weapon is its lair. A GM Intrusion can be used to trigger one of its traps: a PC must make a level 8 Speed defense task or fall 30 feet (9 points of damage) into a chamber, becoming separated from the party.
Hypnotic Lights: As its action, the Predator can activate its lights. All who can see it must succeed on a level 8 Intellect defense task or be dazed, losing their next turn as they are mesmerized by the shifting patterns.
Saw-Nose Rend: This is a level 9 attack that inflicts 10 points of damage and tears through armor, reducing the Armor bonus of any worn armor by 1 permanently.
Bone Claw Skewers: When the Predator hits with a standard attack, it can choose to inflict only 7 points of damage, but the target also begins to bleed, taking 1 point of damage per round until the wound is treated.

Loot: Its corpse yields a wealth of biomaterials. The rostrum can be fashioned into a two-handed weapon, the silk glands can be used to create a cypher that produces a powerful adhesive, and its complex eyes can be used by a Wright to craft an artifact that allows the user to see through illusions.

Pathfinder (2nd Edition)

Labyrinthine Saw-Frog – Creature 13 RARE – N – HUGE – BEAST – AMPHIBIOUS

Perception +25; darkvision, tremorsense (imprecise) 120 feet Skills Acrobatics +21, Athletics +27, Crafting +24 (for traps), Stealth +26 Str +8, Dex +4, Con +6, Int -1, Wis +6, Cha -2

AC 34; Fort +25, Ref +21, Will +23 HP 270

Trapdoor Collapse [reaction] Trigger A creature the saw-frog has detected via tremorsense moves onto one of its hidden pit traps. Effect The triggering creature must attempt a DC 33 Reflex save. On a failure, it falls 30 feet into a subterranean chamber (taking 15 bludgeoning damage) and is stunned 1. On a critical failure, it is stunned 2. The pit remains as hazardous terrain.

Speed 25 feet, swim 40 feet, burrow 25 feet

Melee [one-action] Saw-Nose +28 (deadly d12, reach 15 feet), Damage 3d12+16 slashing Melee [one-action] Bone Claw +28 (agile, reach 10 feet), Damage 3d8+14 piercing plus 1d6 persistent bleed damage

Frenzied Assault [two-actions] The saw-frog makes one Saw-Nose Strike and two Bone Claw Strikes. Its multiple attack penalty increases normally with each attack.

Hypnotic Display [two-actions] (emotion, enchantment, mental, visual) The saw-frog projects a cascade of shifting, colored lights. All creatures in a 60-foot emanation must attempt a DC 33 Will save.

Critical Success The creature is unaffected.
Success The creature is stupefied 1 for 1 round.
Failure The creature is stunned 1 and stupefied 2 for 1 round.
Critical Failure The creature is stunned for 1d4 rounds.

Savage Worlds Adventure Edition

The Pitfall Horror A legendary beast that does not stalk its prey, but invites prey to stalk themselves into its trap-laden home. The creature itself is a terrifying engine of destruction, but the true monster is the ground it commands.

Attributes: Agility d8, Smarts d6(A), Spirit d10, Strength d12+4, Vigor d12 Skills: Athletics d10, Fighting d12, Notice d10, Stealth d12, Swimming d10 Pace: 5; Parry: 8; Toughness: 18 (4)

Edges: Arcane Resistance, Iron Will, Level Headed, Sweep (Improved)

Special Abilities:

Armor +4: Rubbery, thick hide reinforced with chitin plates.
Amphibious: Can breathe in water; Pace is 8″ when swimming.
Burrow (10″): Can disappear into soft earth or mud.
Weapons: Saw-Nose (Str+d10, AP 3, Reach 2″); Bone Claws (Str+d6).
Hypnotic Lights: As an action, the Horror can activate its lights. All who see it must make a Spirit roll at -2 or become Distracted and Vulnerable. With a critical failure, they are Stunned.
Lair (Hazard): The Horror’s territory is a weapon. The GM may require Athletics rolls from the heroes to avoid falling into pits (2d6 damage, potential separation). The Horror can use a Test action against all characters in a Medium Burst Template by stomping and collapsing the ground, attempting to make them Vulnerable.
Size 6 (Large): Attackers gain +2 to attack rolls against it. Its Toughness is increased by 6.
Tremorsense: The Horror is immune to the Drop and automatically detects any creature moving on the ground within a 24″ radius.
Wild Card: The Pitfall Horror is a Wild Card and uses a Wild Die. The Game Master may spend Bennies for it.

Shadowrun (6th Edition)

Geotrap Ambusher This paracritter is a Class-A ecological engineering threat, classified for immediate termination by most corporate and government entities. It does not merely inhabit an environment; it transforms it into a multi-layered deathtrap. Its biology suggests a bizarre magical fusion of aquatic, amphibious, and insectoid genetics, resulting in a patient, cunning predator of terrifying efficiency. It is often the apex predator of any Awakened swamp or abandoned, overgrown urban zone it claims.

Attributes

Body: 10
Agility: 5
Reaction: 5
Strength: 12
Willpower: 6
Logic: 3(A)
Intuition: 5
Charisma: 2
Edge: 5
Essence: 6.0
Magic: 6

Derived Stats

Initiative: 10 + 2D6
Physical Condition Monitor: 13
Stun Condition Monitor: 11
Hardened Armor: 14

Skills: Athletics 6, Close Combat (Exotic Weapon: Saw-Nose) 8, Perception 6, Engineering (Traps) 5, Stealth 7, Unarmed Combat (Claws) 6.

Powers & Qualities

Critter Power (Concealment): The creature’s camouflage is magically potent. It may take a Complex Action to gain this power, which lasts until it moves or attacks. While active, any attack targeting it suffers a –6 dice pool penalty.
Awakened Power (Hypnotic Flash): As a Complex Action, the ambusher can make a Magic + Willpower (12) test against anyone with line of sight. Targets must resist with Willpower + Intuition. Net hits on the ambusher’s test are inflicted as Stun damage, which is resisted only by Willpower.
Critter Power (Natural Weapon: Saw-Nose): DV (STR/2)+4P = 10P, AP -5.
Critter Power (Natural Weapon: Bone Claws): DV (STR/2)+2P = 8P, AP -2.
Critter Power (Tremorsense): The creature has a sensory range of 100 meters for anything touching the ground. It cannot be surprised by physical threats.
Quality (Engineer): The ambusher has an innate talent for creating sophisticated pit traps. Noticing one of its traps requires a successful Perception + Intuition [Mental] (5) test. Failure results in falling into a 10-meter-deep pit.

Starfinder

Geomorphic Ravager – CR 13 XP 25,600 N Huge magical beast Init +4; Senses blindsense (vibration) 120 ft., darkvision 60 ft., low-light vision; Perception +23 Aura hypnotic display (30 ft., Will DC 21)

Defense

EAC 27; KAC 29
HP 255; RP 5
Fort +17; Ref +17; Will +14

Offense

Speed 20 ft., swim 40 ft., burrow 20 ft.
Melee saw-nose +27 (6d8+22 S; critical severe wound) or bone claw +27 (4d6+22 P)
Multiattack saw-nose +21, bone claw +21, bone claw +21
Space 15 ft.; Reach 15 ft. (10 ft. with bone claw)

Statistics

STR +9; DEX +4; CON +6; INT -2; WIS +3; CHA +0
Skills Athletics +28, Stealth +23

Ecology

Environment Warm swamps and riverbeds on terrestrial worlds with high magic or strange biology.
Organization Solitary

Special Abilities

Earth Glide (Ex) The ravager can burrow through stone, dirt, or almost any other sort of earth (except metal) as easily as a fish swims through water, leaving no tunnel or hint of its passage.
Trap-Setter (Ex) As a full action while burrowed, the ravager can create a pit trap in an adjacent 10-foot square. The next time a creature enters that square, they must succeed at a DC 21 Reflex save or fall 40 feet into a pit. The pit is difficult terrain to climb out of.
Hypnotic Display (Su) As a move action, the ravager can cause its skin to flash with hypnotic lights. Creatures within its 30-foot aura must succeed at a DC 21 Will save or be fascinated for 1d4 rounds. A fascinated creature is flat-footed and takes a –4 penalty to skill checks made as reactions. The effect ends immediately if the creature is attacked.

Traveller (Mongoose 2nd Edition)

Subterranean Excavator (Pristis-Major) A semi-sessile ambush predator classified as an Extreme Danger on multiple worlds. This organism does not hunt in a traditional sense; it is a bio-engineer that transforms its habitat into a lethal landscape. Its presence is often only detected after colonists or survey teams suffer catastrophic losses from seemingly natural ground collapses. Its physiology is a bizarre amalgam, defying easy classification.

STATS: EAACAA-E A-10 1 Age(20), Armour(8), Burrow(2), Fear(1), Natural Weapon(Saw/Claws), Recon(3), Size(14), Stun(Light), Tremorsense, Walker

STR 14 (+4), DEX 10 (+2), END 10 (+2)
Skills: Athletics (DEX) 2, Engineering (INT) 3, Fighting (Unarmed) 2, Recon (INT) 3, Stealth (DEX) 3, Survival (INT) 3
Attacks: 1 per round
Damage (Saw-Nose): 6D, AP 6
Damage (Bone Claws): 4D
Armour: 8 points of natural plating.
Health: 34 (Sum of physical stats)

Traits & Behavior:

Burrow: The creature can burrow through 2 meters of soft earth per round.
Tremorsense: The creature is aware of any ground vibrations within 200 meters. It cannot be surprised by land-based movement.
Stun (Hypnotic Lights): As an action, it can flash a bio-luminescent pattern. Any character with line of sight must make a Difficult (10+) END check or be stunned and unable to act for 1d6 rounds.
Trap Lair: The excavator’s territory is a deathtrap. When travelling through its lair, the Referee should roll 2D every 10 minutes; on a 10+, a character has triggered a pit trap. They must make a Difficult (10+) DEX check to avoid falling 10 meters (taking 10D of damage) into a subterranean chamber.
Solitary: These creatures are always found alone. They are highly territorial and will attack other excavators on sight.

Warhammer Fantasy Roleplay (4th Edition)

The Bog-Sinker A creature of Old World nightmares, said to dwell at the heart of the Great Swamp and in the deepest, most inaccessible marshes of the Empire. The Bog-Sinker is a monster of immense size and cunning, a living manifestation of the land’s hunger. It does not chase its victims; it lets them walk into its embrace, for the very ground in its territory is a weapon shaped by its patient, malevolent will.

Profile | WS | BS | S | T | I | Ag | Dex | Int | WP | Fel | | :–: | :–: | :–: | :–: | :–: | :–: | :–: | :–: | :–: | :–: | | 70 | – | 65 | 70 | 45 | 40 | 25 | 30 | 60 | 5 |

Skills: Athletics 50, Endurance 85, Melee (Basic) 80, Perception 75, Stealth (Rural) 65 Talents: Armour Piercing 3 (Saw-Nose), Fear 3, Iron Jaw, Menacing, Monstrous Creature, Night Vision, Relentless, Strike to Stun Traits: Armour (All) 5, Bite (Saw-Nose) +13, Size (Enormous), Swallow Whole, Swamp-Strider, Terror 3, Tremorsense, Trap-Maker, Hypnotic Glimmer, Weapon +10 Wounds: 76

Attacks

Saw-Nose: WS 70, Damage S(6)+Weapon(10)=16. Has the Hack and Impale Qualities.
Bone Claws: WS 70, Damage S(6)+Weapon(0)=6. Does not use its full strength in these faster attacks.

Special Rules

Swallow Whole: If the Bog-Sinker inflicts a Critical Wound on a target of Average size or smaller with its Bite, it can choose to swallow them. A swallowed victim is trapped and suffers a Damage 10 Hit that ignores armour at the start of each round. They may attempt to cut their way out by inflicting a total of 20 Wounds with a dagger or similar small weapon.
Tremorsense: The Bog-Sinker automatically detects anything moving on the ground within 60 yards. It cannot be Surprised.
Trap-Maker: The Bog-Sinker’s lair is riddled with pit traps. At the start of each round, the GM can nominate one character in the lair. That character must pass a Hard (–20) Athletics Test or fall 20 feet into a pit, suffering a Damage 10 Fall and gaining the Prone Condition.
Hypnotic Glimmer: As a Full Action, the Bog-Sinker can flash patterns on its skin. All who can see it must pass a Challenging (+0) Willpower Test or gain 1 Stunned Condition.