Bestiary
Every third thing you meet down here would rather be your friend than your food. The trouble is telling the third things apart — and remembering that even a friend of the Deep answers to the Deep first.
— Sporefather Umble, of Softloam
The creatures gathered here are the common life of the low Reaches — the fauna and folk a party is most likely to meet between the Downstair Gate and the edge of the Bruise. Some graze the spore-meadows and want nothing from you. Some tend the great Weave with a patience older than your bloodline. And some have already been unmade by the Blight Below and remade into its hunger, wearing the shapes of gentler things. Each entry opens with a note on where the creature lives and how it behaves, followed by its stat block in the current format. Challenge ratings run from 0 to 8; the greater horrors of the deep Reaches wait in Part B.
The Lesser Deep (CR 0–1/2)
The smallest lives of the Mycelial Deep drift, graze, and gnaw at the edges of every settlement. Alone they are little threat; in the Deep, though, almost nothing travels alone.
- Mote-Sprite
- Gillhopper
- Sporeling
- Gnawcap
- Glimmereel
- Velvet Ox
- Myconid Tender
- Silkling
- Blightspawn Crawler
- Spore-Zombie
Wardens, Hunters, and Herd-Beasts (CR 1–2)
Between the harmless and the horrifying stands a middle tier: the circle-wardens that keep the peace of the Weave, the predators that keep its balance, and the first corrupted things strong enough to hunt a party rather than merely infect it.
- Blight-Hound
- Gillforest Silk-Spider
- Myconid Warden
- Pale Voice
- Rutting Spore-Bull
- Lumen Lurker
- Chorus-Hound
- Blightthrall
- Sporewight
The Deeper Reaches (CR 3–5)
Deeper in, the Weave grows stranger and its keepers grow stronger. Here dwell the song-keepers of the Sporesung, the first true monsters of the Bruise, and the gentle giant that gives this bestiary its most beloved face.
- Chorister Myconid
- Weeping Rot
- Blightspawn Ravener
- Silk-Weaver Matron
- Drowned Continuant
- Lantern Shepherd
- Pale Chorister
- Blight-Shroudcat
Apex of the Low Bestiary (CR 6–8)
At the top of the low bestiary stand creatures a starting party should flee: a relic-lord devoured by its own symbiotes, the leviathan of the glowing lake, the loom-tyrant that eats its rivals to grow, and the walking masterpiece of the Rustgyre. These are the doorways to the horrors of Part B.
Bestiary –- Apex Threats
The creatures gathered here are the Deep's deep water. Where the earlier bestiary catalogued the beasts a caravan might survive, these are the things a caravan is a rumor to — the horrors the Sporesung sing wards against, the titans the Marrow Roads were carved around rather than through, and the singular, waking dreads that the Weave itself seems to hold its breath near. Most inhabit The Bruise, the deep Marrow Roads, and the soft-reality edges of the Heartweave, and several are less monsters than arguments the Blight Below is making about what a self should be. Read their lore aloud before you place their blocks: a party that understands what a thing wants will fear it long before it rolls Initiative.
You have heard the Deep hum since the Downstair Gate. Here the hum changes. It is no longer the sound of a place that is alive. It is the sound of a place that has noticed you — and has, at last, an opinion.
The Gillreaper Stalker
The Blightfen Weepwood
The Sporeglass Basilisk
The Charnholt Ossuar
The Rustgyre Chorus-Thrall
The Hush-Canopy Silkwidow
The Bracketways Wing-Tyrant
Lord-Continuant Ashveil
The Suppuratehold Rotmother
The Reliquary Lord of the Pale Manse
The Marrowmaw Delver-Wyrm
Legendary Threats of the Deep
The creatures that follow are singular. Each has Legendary Resistance (typically three uses per day, and a fourth while it defends its lair), Legendary Actions it may spend between other creatures' turns, and a lair whose Lair Actions and regional effects are described in prose after its block. Treat a fight against any of them as terrain first and monster second: their lairs are the Deep itself taking a side.
Oneiroth, the Dreaming Wound
Lair Actions. Within the soft-reality of the Heartweave — the Dreaming Bloom, the Rememberers' Grove, or wherever it first tore free — Oneiroth warps the dream around it. On Initiative count 20 (losing ties), Oneiroth takes one Lair Action, choosing an effect it hasn't used the previous round: the walls become a remembered place and a creature Oneiroth can see must succeed on a DC 19 Wisdom save or relive its worst fear, gaining the Frightened condition and moving its full Speed toward the nearest hazard; or a doorway opens onto elsewhere and up to two creatures within 30 feet of each other are teleported (a failed DC 19 Charisma save) to swapped positions or to another point in the lair; or the dreaming dead speak, and each creature that isn't an Aberration in the lair takes 11 (2d10) Psychic damage unless it stops to listen (a DC 19 Wisdom save).
Regional Effects. While Oneiroth lives, the region within 1 mile of its lair is dream-touched: creatures that sleep there wake remembering lives that were never theirs; spores show fragments of the past to any who breathe them; and the boundary between what is dreamed and what is real thins, so that a strong enough belief can briefly reshape small features of the terrain. These effects fade over 1d10 days after Oneiroth is slain.
Charnhulk, the Marrow Colossus
Lair Actions. On the Ribways and in the Skull Vault, the road is Charnhulk's body by proxy. On Initiative count 20 (losing ties), Charnhulk takes one Lair Action it didn't use the previous round: the bone-road heaves, and each creature on the ground within 60 feet makes a DC 19 Dexterity save or gains the Prone condition and is Restrained (escape DC 19) by grasping fingers of bone; or the marrow of the road exhales, and each creature within 30 feet of a point Charnhulk chooses makes a DC 19 Constitution save or gains the Poisoned condition until Initiative count 20 on the next round; or walls of interlocking rib close a chosen 20-foot passage, requiring a DC 19 Strength check or a turn's work to clear.
Regional Effects. While Charnhulk walks, the Marrow Roads within 1 mile grow restless: buried bones twitch toward it, the continued dead do not rest and may rise as lesser ossuars, and tremors make delving treacherous (Difficult Terrain on unstable ground). These effects fade over 1d10 days after Charnhulk is destroyed.
The Choir-Drowned
Lair Actions. The Mourning Glass is the Choir-Drowned's body by other means. On Initiative count 20 (losing ties), it takes one Lair Action it didn't use the previous round: the black water surges in a chosen 20-foot-radius area, and each creature there makes a DC 19 Strength save or is dragged Prone into the flood and has the Grappled condition (escape DC 19) as reaching hands close on it; or the lake shows a creature its own drowned face, and one creature the Choir-Drowned can see makes a DC 19 Wisdom save or has the Frightened condition until Initiative count 20 on the next round; or the surface exhales a grieving mist, and the lair becomes Lightly Obscured while each creature that isn't Undead takes 9 (2d8) Cold damage on a failed DC 19 Constitution save.
Regional Effects. While the Choir-Drowned haunts it, the region within 1 mile of the Mourning Glass turns funereal: still water everywhere shows the faces of the drowned dead and murmurs their names; creatures that sleep on its shores wake grieving and gain no benefit from the rest unless they succeed on a DC 15 Wisdom save; and a corpse left overnight within a mile too often rises at dawn and walks toward the lake to join the chorus. These effects fade over 1d10 days after the Choir-Drowned is destroyed.
Old Reachthorn, the Rogue Leviathan
Lair Actions. The tunnels Reachthorn has grown through are all, in truth, one body. On Initiative count 20 (losing ties), Reachthorn takes one Lair Action it didn't use the previous round: thorns erupt from any wall, and each creature within 10 feet of a surface makes a DC 19 Dexterity save or takes 22 (4d10) Piercing damage and gains the Restrained condition (escape DC 19); or the passage constricts, halving the Speed of each non-plant creature within 60 feet until Initiative count 20 on the next round; or the spores turn coaxing, and one creature Reachthorn can see makes a DC 19 Wisdom save or moves toward Reachthorn by the shortest route on its next turn.
Regional Effects. While Reachthorn lives, the Weave within 1 mile of its lair turns predatory: symbiotes grow wild and aggressive, ordinary spore-blooms reach for warmth like feeding things, and every bonded creature in the region makes Communion saving throws with Disadvantage as the ancestor of all their symbiotes tugs at the bond. These effects fade over 1d10 days after Reachthorn is slain.
Suppuration, the Weeping Seed
Lair Actions. The Rustgyre is Suppuration's garden and its body's outermost reach. On Initiative count 20 (losing ties), Suppuration takes one Lair Action it didn't use the previous round: the spore-storm surges, and the whole lair becomes Heavily Obscured until Initiative count 20 on the next round while each creature that breathes makes a DC 20 Constitution save or is exposed to blight; or the ground blooms teeth, and each creature on the ground within 60 feet of a point Suppuration chooses makes a DC 20 Dexterity save or takes 22 (4d10) Piercing damage; or the war-dead of the Weeping Front rise, and 1d4 blightspawn or a Rustgyre Chorus-Thrall claw up from the rot to fight for the seed.
Regional Effects. While Suppuration blooms, the region within 1 mile is consumed at the rate of roughly a mile a bloom: the weather is a permanent Rustfall of blight-fog, healing magic functions at half effect, and every bonded creature that can see Suppuration makes Communion saving throws with Disadvantage. These effects recede over 1d10 days only if the seed is truly destroyed; otherwise they endure.
The Pale Chorus Avatar
Lair Actions. Within a fully sung site — the Chorus Pits, or a settlement wholly assimilated — every surface is part of the Avatar. On Initiative count 20 (losing ties), the Avatar takes one Lair Action it didn't use the previous round: the lair sings, and each creature that can hear makes a DC 21 Wisdom save or has the Charmed condition until Initiative count 20 on the next round, drawn toward the nearest assimilated surface; or the air carries the “cure,” and each creature in the lair makes a DC 21 Constitution save or is exposed to blight; or the assimilated dead rise from the walls, and up to four Rustgyre Chorus-Thralls or a swarm of blightspawn claw free to sing alongside their maker.
Regional Effects. While the Avatar exists, the region for miles bends toward it: individuals feel a persistent, gentle pull to confess their pain and merge, the spore-song is heard in dreams as far as the Velvetfields, and the Weave answers the Chorus's call rather than the Sporesung's — healing prayers falter, and continued dead wake as thralls. These effects fade over 1d10 days after the Avatar is truly and finally silenced, if it ever is.