Marrowborn Lair: Cystern

Marrowborn Cystern

An alien landscape of slow death and excruciating pain, a cystern serves as a lair for the infectious undead known as the marrowborn. A cystern can be constructed just about anywhere by a Marrowborn Empress, though the matriarchal monster seeks out locations with a few requirements in mind. These are in order of this priority; covertness, defensibility, spaciousness, and mobility.

As such most cysterns are created within abandoned fortresses or dank caverns that are reasonably close to humanoid populations. The empress needs those poor souls to create Marrowborn Pawns from their skeletal structure. However, the cystern may be formed within the sewer system underneath a major city, the depths of a steaming jungle, or the hull of a listing galleon along a shipping route. Sometimes, an empress may found a chain of cysterns to better propagate her brood and ensure it would be very difficult to wipe them all out.

The interior of the cystern is a grand, profane cathedral with sweeping buttresses of sculpted bone, chandeliers of mucus-slicked sinew, and windows of stretched organs collected in a mockery of stained glass. The floor is tiled by interlocking bone plates alternating between rot-blackened and polished white. Under the ossein blocks lies a swath of cushioning, grey muscle and ichor-filled veins. The doors are great arches that are sometimes filled with knuckle-bone curtains, undead sphincters, or cartilage shades. The interior layout of the building is changed as well with only supporting walls and columns remaining while the rest is remade much like the interior of a paper nest, save the material is harvested flesh and bone.

Regional Effects.

- Rank mist lightly obscures the land within 6 miles of the cystern.

- Creatures within 6 miles of the cystern suffer disadvantage when saving against Disease.

- Foodstuffs within 1 mile of the cystern go bad and rot at three times the rate.

Locations:

Empress’ Throne. Located at the core of the cystern is the marrow empress’ private chamber. When not seeing to her kin, the undead abomination rests on her nest of upturned bone and oozing grey meat that takes the form of a massive throne ringed by hooked barbs. Here she is attended to by favored marrowborn pawns and Marrowborn Partisans who will fanatically defend her to the death. The pawns bow and scrape in mute supplication while the partisans coil at the base of her throne ready to swiftly dispose of those that displease the empress. Often one can encounter a Marrowborn Consort here as well, when the fellow is not off tending to other sections of the cystern.

Optional Mechanics

The empress’ throne provides Lair Actions to the marrowborn empress. Fighting the marrowborn empress at the empress’ throne increases her CR to 13.

-Part of the floor or wall animates as a grasping extremity of shattered bone and attacks one target that the marrowborn empress can see within 60ft of it. The target must succeed on a DC 15 Strength saving throw or take 10 (3d6) piercing damage and are grappled (escape DC 15). For the next minute, if the creature does not escape at the end of its turn it takes an additional 10 (3d6) bludgeoning damage as it is crushed. The extremity has a speed of 15ft and will take the creature of it is medium size or less with it, but it cannot leave the empress’ throne.

-The empress attunes her senses to the bone floor and walls and extends her blindsight to the entire empress’ throne. Until initiative count 20 next round she has advantage on attack rolls, ability checks and saving throws as long as she remains in the empress’ throne.

-The empress drews the rot from within the cystern and fills the area with noxious gas. This fills a 20ft sphere centered at a point she can see within 60ft with poisonous gas for the next 30 seconds (5 rounds). When a creature enters the sphere for the first time or starts its turn within in it must succeed on a DC 15 Constitution save or take 10 (3d6) poison damage and be poisoned until the end of its turn.

-The empress creates a swarm of miniscule marrowborn out of the empress’ throne’s interior and sics them on a target she can see within 30ft. The target must succeed on DC 15 Dexterity save or take 10 (3d6) piercing damage and suffer disadvantage on attack rolls and ability checks for the next minute or until they regain hit points.

Brooding Pit. The largest space in the cystern is reserved for housing humanoid victims implanted with marrowborn cysts. The brooding pit has no tiles, only a spongy floor of undead meat ringed by a high bone railing to keep the suffering housed. It stinks of offal, rot and death. The only thing the wretched incubators have to feed on is the shed flesh of those that came before them. Marrowborn Rooks are usually stationed here. The towering anathemas not only guard the pit from external foes, but keep the infected from escaping. It is not uncommon for the rooks to break the limbs of especially stubborn humanoids and deal with fixing the marrowborn birthed from them later.

Optional Mechanics

Stench Belch. The brooding pit produces a noisome, choking cloud on Initiative count 20, losing ties. Creatures within the brooding pit must succeed on a DC 13 Constitution save or be Poisoned until the end of their next turn. Constructs, undead, oozes are immune to Stench Belch.

Sentry Corridors. Labyrinthine in their layout, the sentry corridors connect the various rooms of the cystern. Their seemingly haphazard layout and frightening nature confuses and demoralizes intruders as they make their way through them. Marrowborn, on the other hand, travel them by rote with all the concern of ants in their hive. Marrowborn rooks and Partisans patrol the halls when they are not caught up in other duties and pawns roam them at all hours.

Optional Mechanics

Growing Madness. Each time a creature enters a new section sentry corridor from another sentry corridor they must succeed on a DC 13 Wisdom save or become disoriented. Their movement speed is halved for the next minute as they try to navigate while in a fugue. At the end of each of their turns, an affected creature may repeat this wave with the effect ending on success. Constructs and undead are immune to this effect.

Red Sanctuary. One might call the red sanctuary the spiritual center of the cystern save the marrowborn are soulless voids. These crimson spaces are the domain of the hive’s Marrowborn Cardinals. Here the aberrant arcanists research dread magics and develop new marrowborn mutations. Thankfully, the cardinals’ minds are as dimmed as the rest of the undead horde, so the progress is slow. The walls of this room continuously seep blood drained from the rest of the cystern. The marrowborn cardinals dip their foul tongue-tips into the vitae and use it to scribe their alien treatise.

Optional Mechanics

Blood Tithe. The walls crave blood and draw it from open wounds of living creatures within the room on initiative count 20. All creatures that are currently at less than their maximum hit points within the red sanctuary must succeed on a DC 13 Constitution save or take 2d8 necrotic damage. Constructs, undead, and oozes are immune to blood tithe.

Holding Sacs. As the Marrowborn Pawns of the cystern increase so does the need for housing for the multitude. The holding sacs are situated through the cistern, seamlessly filling in the space between its vile walls. Within these vessels, the pawns curl into a tight, fetal position as they float within fire-resistant phlegm. Each sac has two sphincter openings from which it can spit out the pawns it contains at a rapid-fire pace.

Optional Mechanics

Spawn Pawns. The holding sac spits out marrow pawns ready to defend the hive on initiative count 20, losing ties. A marrowborn pawn is spawned in an unoccupied space within 5ft of both sphincters of the holding sac. These marrowborn pawns act on initiative count 10.

Each sphincter has an AC of 12 and 30 hit points. Once a sphincter is reduced to 0 hit points it cannot spawn a marrowborn pawn until repaired.

Sinew Stables. The sinew stables are not stables, per say. In truth, these spaces have more in common with holding sacs. Instead of being mostly inserted in between walls, the sinew stables stretched between the vaulted rafters like glistening spiderwebs. The sinew stables also provide an extra level of stabilization to the entire structure. This is where the Marrowborn Partisans lurk and rest when not patrolling the sentry corridors or protecting their empress. The centipede-like horrors can navigate the web with little difficulty and deposit themselves into the various rooms and halls of the cystern from above.

Option Mechanics

Moving across the sinew stables counts as difficult terrain unless a creature has a climb speed but marrowborn partisans ignore this effect. When moving across the sinew stable, marrowborn partisans gain advantage on Dexterity (Stealth) checks.