Skip to content
CharGen Icon
CreatePricing
Siltstalker - AI-generated fantasy Monster

Siltstalker

Dungeon workers tell of a shape that follows the smell of fresh oil and soaked rope, appearing where lanterns gutter and the floor turns slick. Old tunnel maps mark certain bends with warnings scratched into stone: do not linger in the blue-dark water. The siltstalker is blamed for missing porters, torn packs, and the eerie sound of something breathing through a grate just before an attack.

Monsters
Medium monster · Low to Moderate · uncommon

Siltstalker

A flood-dwelling tunnel predator warped by underdark seepage and the scent of enchanted lantern oil. It hunts supply corridors, broken drains, and half-submerged chambers where weak light and muffled footsteps make travelers easy to isolate.
AC13
HP45/45
CRLow to Moderate
Init
STR
DEX
CON
INT
WIS
CHA
ConditionsNone

Combat

AC 13 · HP 45 · Low to Moderate

Siltstalker

Medium monster (beast), unaligned
Armor Class13 (natural armor)
Hit Points45 (6d10+12)
Speed
30 ft.,
swim 40 ft.
STR
DEX
CON
INT
WIS
CHA
Saving ThrowsDexterityConstitution
SkillsPerceptionStealthSurvival
Damage Resistances
necrotic damage while submerged in water or standing in heavy shadow
Immunities
prone while swimming or submerged in water at least 1 foot deep
Weaknesses
Bright continuous light imposed on its lair suppresses its ambush advantage.
Running water or sudden flooding can dislodge its footing and expose it to attacks.
Fire that spreads across oil slicks can deny it the watery lanes it prefers.
It is vulnerable to effects that reveal invisible or hidden creatures in water and darkness.
Senses
darkvision 60 ft.,
blindsight 10 ft. in water,
passive Perception 13
Languages
understands Undercommon but can't speak
ChallengeLow to Moderate
Proficiency Bonus+2
Passive Perception13
Darkwater Stalker. The siltstalker has advantage on Dexterity (Stealth) checks in dim light, darkness, or while partially submerged in water. It can also attempt to Hide when only lightly obscured by spray, steam, or a broken grate.
Oil Scent. The siltstalker has advantage on Wisdom (Perception) and Wisdom (Survival) checks that rely on smell. It knows when a creature within 60 feet is carrying lamp oil, enchanted oil, or fresh wicks if the scent is not masked.
Mire Glide. The siltstalker has a swimming speed and can move through shallow water and muddy rubble without penalty. A flooded square or channel does not count as difficult terrain for its movement.

Actions

Snap Maw. Melee Weapon Attack: to hit, reach 5 ft., one target. Hit: 10 () piercing damage plus 3 () necrotic damage. If the target is Medium or smaller, it must succeed on a Strength saving throw or be pulled up to 10 feet straight toward the siltstalker.
Drain Slip. The siltstalker moves up to half its speed without provoking opportunity attacks. During this movement, it can move through a 1-foot-wide opening, such as a cracked drain or broken grate, as if it were difficult terrain.
Tail Lash. Melee Weapon Attack: to hit, reach 10 ft., one target. Hit: 8 () bludgeoning damage, and the target must succeed on a Constitution saving throw or have disadvantage on its next Wisdom (Perception) check before the end of its next turn as briny muck and snapped fibers clog its senses.

Reactions

Ambush Flare. When a creature the siltstalker can see enters a space adjacent to a grate, drain, or flooded corner, the siltstalker moves up to 10 feet to a space it can see adjacent to that creature. This movement does not provoke opportunity attacks.
Role
ambusher and tunnel predator
Built for
1-3

Gear

  • Shredded Wick Nest (Trophy, 0 gp)A nest of snapped lantern wicks, usable as foul-smelling tinder or evidence of its presence.
  • Silt Oil Sac (Alchemical Trophy, 5 gp)A thin flask of black slick extracted from the creature's hide, useful only as a clue or alchemical ingredient.
  • Broken Supply Harness (Salvage, 2 gp)If the creature has recently killed a merchant or porter, it may wear a half-ruined carrying strap with one intact supply tag.

Feats

Darkwater Camouflage
Scent of Oil
Corner Ambusher

Notes for the game master

The siltstalker gains advantage on Dexterity (Stealth) checks made in dim light, darkness, or while partially submerged.
While in water at least 1 foot deep, it can move through enemy spaces as if they were difficult terrain, but it must end its movement in an unoccupied space.
If the siltstalker hits a creature carrying lantern oil, alchemical oil, or a similar pungent supply, it can smell that target even if it is hidden, provided the target is within 60 feet and not behind total cover.

Tactics

  1. Opening

    It waits submerged or motionless behind broken masonry until the party enters a weak-light zone, then strikes the rear rank or the torchbearer with Snap Maw, aiming to separate the group.

  2. Mid-fight

    It circles through flooded side passages, using Drain Slip to reposition, then lunges from cover to pull a target off balance. It favors lightly armored, isolated characters and any creature carrying bright oil, lantern supplies, or a strong scent of blood.

  3. End of the fight

    When bloodied, it becomes reckless and defensive, snapping at the nearest wounded foe while trying to drag prey back into knee-deep water or behind a bend where ranged allies have poor sightlines.

  4. Retreat

    If reduced to 6 hit points or fewer, it tries to vanish into a grate, culvert, or deeper floodwater rather than fight to the death. It flees if it cannot reach water within one round or if the party floods the corridor with bright, steady light and fire it cannot easily cross.

How it fights

Hide in a flooded corner or behind a broken wall until prey is within reach.
Strike the supply carrier or lantern bearer first.
Pull one target toward water, then disengage through a drain.
Use corners and grates to break line of sight and force the party to advance cautiously.

Who it attacks first

Characters carrying lantern oil, supplies, or bright lights.
Isolated backliners.
Wounded targets that can be dragged into water or around a corner.

Works well with

Pairs well with collapsing ceilings, slick floors, and tight corridor fights.
Works as a scout for deeper dungeon threats by softening up the party and separating the rear guard.
Combines effectively with enemies that can block exits or exploit darkness.

How to beat it

Bright continuous light that floods the corridor makes its ambushes much less effective.
Spells or effects that create difficult terrain, seal drains, or control water can limit its movement.
Forcing it into dry, open ground reduces its mobility and denies it easy concealment.
A strong, pervasive scent such as alchemist's fire, incense, or heavy smoke can mask the smell of supplies and living prey, making ambushes harder for it to time.
Ready actions at corners, grates, and flooded thresholds punish its sudden lunges.

Ways to avoid a fight

It can be lured with the scent of oil, raw meat, or blood into a prepared kill zone.
A successful DC 13 Wisdom (Animal Handling) check might keep it at bay long enough for the party to pass if someone remains calm and keeps bright light between them and the water.
A DC 13 Intelligence (Investigation) check can identify the safest path by spotting drag marks, oil residue, and the narrowest wet choke points.
It may be driven off by flooding a corridor with roaring light, noise, or steam, forcing it to abandon its preferred ambush terrain.

Ecology

A siltstalker is a low-slung, eel-jawed tunnel beast with slick black-green hide, pale blind eyes, and a mane of ropey algae that drifts behind it in the water. Its shoulders are crusted with grime and mineral scale, and snapped wick fibers cling to its teeth like shredded straw. When it rises from a flooded channel, lantern light slides across its wet back in broken glints, making it seem larger than it is.

Behavior

Patient, opportunistic, and territorial. It prefers to stalk in silence through shallow water, then attack with a single explosive rush when prey is distracted by terrain or conversation. It is drawn to the smell of enchanted oil, wet rope, tallow, and panic.

How it lives

Siltstalkers nest in flooded service tunnels, undercroft culverts, and collapsed maintenance shafts where water pools knee-deep and footing is treacherous. They feed on rats, bats, lost scouts, and any caravan animal unlucky enough to stumble into their lairs. In older ruins, they often inherit the territory of forgotten guardians and twist it into an ambush route.

Lair

Its lair is usually a drowned junction chamber with three features: a shallow central pool, at least one cracked drain or grate, and a narrow dry shelf where it stores stolen supplies. The ceiling is often webbed with mineral growth and old wick fibers, and the water surface is littered with oil sheen, bones, and broken corks.

Habitat
Flooded dungeon floors, submerged supply tunnels, drainage channels, ruined culverts, underdark spillways, and narrow corridors with broken stone and weak lantern light.

Signs that it is near

Slick oil films broken into rainbow patches on stagnant water.
Algae strands snagged with pale wick fibers.
Deep drag marks in mud that vanish under a grate or broken culvert.
Small bones and pack ties collected in a drain corner.
A wet, guttural clicking sound from beyond the next bend.

Tags

flooded dungeon,
predator,
ambusher,
darkness,
underdark corruption,
early-floor encounter,
guardian warped by shadow

Lore

Dungeon workers tell of a shape that follows the smell of fresh oil and soaked rope, appearing where lanterns gutter and the floor turns slick. Old tunnel maps mark certain bends with warnings scratched into stone: do not linger in the blue-dark water. The siltstalker is blamed for missing porters, torn packs, and the eerie sound of something breathing through a grate just before an attack.

What drives it

Hunger, territory, and attraction to the scent of enchanted oil and warm living bodies.

After the fight

If the party defeats the siltstalker, they may recover intact lantern oil ampoules, shredded wick bundles, and a scrap of tunnel warding charm tangled in algae. The supplier might be found alive nearby, hidden in a maintenance pocket or trapped behind a jammed flood door. Townsfolk who learn of the creature gain a grim respect for the dungeon and the supply route it guards.

“Old tunnel maps mark certain bends with warnings scratched into stone: do not linger in the blue-dark water.”
From its lore

Variants

Grate-snarler siltstalker, with longer foreclaws and a stronger pull into drains.
Blind drudge siltstalker, a more mindless version with higher stealth in darkness but weaker tactics.
Corrupted tunnel guardian siltstalker, bearing rusted ward-plates and faint rune scars.

Hooks

Plot hooks

The missing supplier has been cornered in the siltstalker's lair, but rescuing them requires crossing a flooded ambush tunnel first.
The creature has begun stealing lantern oil, threatening the town's night wards unless the party clears the route.
A map recovered from the dungeon shows the beast's hunting grounds overlap with a sealed underdark gate.
The siltstalker may be the warped remnant of an old tunnel guardian, and restoring the warding sigils could calm or banish it.

How to use it

An early-floor ambush in a flooded supply corridor.
A stalking predator shadowing the party while they escort a frightened supplier.
A guardian of the last intact cache of enchanted oil or wick fiber.
A pressure-test encounter that teaches caution around corners, grates, and weak light.

Treasure

1d4 intact lantern oil flasks or wick bundles, if the creature has been feeding in a supply route.
A small chance of a minor charm, tunnel token, or collapsed cache key hidden in its lair.
Useful salvage from the drowned supply run, including rope, corks, and a partly preserved map case.

Media

0 images

No images yet.

Visual sheet

Turn Siltstalker into a sheet

A high-res, share-ready sheet you can post or print.