Cathedral of the Immaculate Conception

Main Entrance

You step through the massive, weathered doors into the ruined cathedral, and your breath catches in your throat. The air is thick with dust and incense, long since settled into the cracked tile floor. Before you stretches the grand nave—rows of splintering pews lined beneath shattered stained-glass windows that cast fractured, spectral light across the debris-strewn stone. The once-majestic vaulted ceiling looms high above, webbed with age and shadow. Faint whispers seem to echo between the columns, and at the far end, the altar lies in eerie silence, half-shrouded by a collapsed beam and overgrown vines. A faint scent of old blood and damp stone lingers, as if the cathedral itself is holding its breath, watching your every move.

There are two hell hounds in this room. The party cannot see them when they first come in the room from this door. They do not have line of sight on them until they are even with the last pillars. The dogs will attack at that point and the players might be surprised. The Hell Hounds have a stealth score of 9. Compare this to the players passive perception check which is likely to be higher, unless they have some kind of penalty.

South Entrance

You slip in through the heavy side door, the hinges groaning just enough to send a shiver up your spine. The room you enter is dim, lit only by what light filters through the fractured stained glass above. You find yourself in a narrow antechamber just off the grand cathedral hall—its stone floor cold beneath your boots, scattered with wilted prayer scrolls and broken votive candles. To your right, there is a door. In front of you is the main sanctuary where the pews stretch in solemn rows, but here it feels closer, more intimate. The air carries a strange mix of incense and rot. A toppled statue of a weeping angel lies face-down beside an old confession booth, its wood cracked and darkened with age. You can hear something moving faintly beyond the pillar—a scraping sound, rhythmic and slow. Then it steps out of the shadows. Its body a blackened mass of charred muscle and cracked obsidian-like skin, glowing from within with the relentless heat of eternal fire. Flames pour from its eyes, mouth, and along its spine, licking the air with a furious hunger as molten embers fall in its wake. This creature is no ordinary beast—it is a living inferno born of destruction, its growl like the rumble of a collapsing world

The door on the right hand side is locked.

The party can see the first Hell Hound from here, but cannot yet see the second one that is by the other front pillar, next to the stairs to the podium.

South West Chamber

You step through the doorway on the left into a dimly lit, lavishly decorated chamber. The first thing that catches your eye is the large, elegant carpet dominating the center of the room—its dark diamond-patterned design bordered in deep gray, evoking a sense of wealth and austerity. A long, metallic containment units serves as the centerpiece sitting atop the rug, its smooth sheen faintly reflecting the low light. Against the south wall, sits a sleek red cushioned bench—immaculate and untouched—while two high-end display cases, built into the northern wall, cradle mysterious objects under glass, their faint glow adding a subtle ambiance. The walls around you curve subtly, creating a semi-octagonal structure that gives the space a refined, almost ceremonial feel. The atmosphere is quiet… too quiet.

The large containment unit contains the ash that Ilsa created to use for the Oath of Ash. Breaking this open will result in anyone within 5 feet being contaminated by the ash. Use the breaking objects rules in the scavenging rules for breaking into the containment unit. Alternatively, the unit will unlock if Ilsa's blood is applied to the top surface.

Oath of Ash

Any character that comes into contact with the Oath Ash will be exposed to the Sonohoka Syndrome virus and will need to roll saves accordingly. If they are at 50% or more of their life total they make a Con save DC 10. If they are less then 50% of their life total they make a Con save DC 10 with disadvantage. Failing the save means that they are infected with the virus while success means that they are not.

If they become infected, they will progress through the stages of the disease as described below.

Day 0.

On the day of exposure, the person does not yet experience any symptoms.

Day 1.

At the start of the day, fatigue and body aches are the first symptoms to settle in. They gain 1 level of exhaustion.

Day 2.

At the start of the day, the fatigue and body ache worsens. They gain 1 level of exhaustion.

Day 3.

At the start of the day, the fatigue and body ache worsens. They gain 1 level of exhaustion. Additionally, the manifestations of the mutations begin. At this stage, they could reasonably hide the mutation.

Day 4.

At the start of the day, the fatigue and body ache worsens. They gain 1 level of exhaustion. The mutations continue to progress, becoming more apparent. At this stage it would be difficult to hide the mutation. At the end of the day, they roll a Con Save DC 15. Failing this save means they continue to progress through the stages of infection as described below. If they pass the save, then their immune system was able to fight off the virus and they have no further progression through the stages of infection. However, they are now an Other. The mutations that have manifested are a permeant part of their biology.

Day 5.

At the start of the day, the fatigue and body ache worsens. They gain 1 level of exhaustion. The mutations fully manifest. They can no longer reasonably hide their mutation. At the end of the day, they roll a Con Save DC 15. Failing this save means they continue to progress through the stages of infection as described below. If they pass the save, then their immune system was able to fight off the virus and they have no further progression through the stages of infection. However, they are now an Other. The mutations that have manifested are a permeant part of their biology.

Day 6.

At the start of the day, the fatigue and body ache becomes completely crippling. They roll a Con Save DC 15. Failing this save means they succumb to the infection and become a Zombie. They loose all levels of fatigue as the infection has run its course. They become an NPC. If they pass the save, then their immune system was able to fight off the virus and they have no further progression through the stages of infection. However, they are now an Other. The mutations that have manifested are a permeant part of their biology.

Mutations

Ilsa has used science and magic to engineer a strain of the virus that creates mutations like her own. Any character that develops mutations will gain the following manifestations:

Day 3 mutation: Become immune to fire damage and their skin begins to darken.

Day 4 mutation: They gain the "Heated Body" feature. A creature that touches the character or hits it with a melee attack while within 5 feet of it takes 5 (1d10) fire damage.

Day 5 mutation: They gain the "Illumination" feature. The character sheds bright light in a 10-foot radius and dim light for an additional 10 ft. Their body is now blackened and burning.

Day 6 mutation: They gain the "Heated Weapons" feature. When the character hits with a metal melee weapon, it deals an extra 3 (1d6) fire damage.

Note: each time a character manifests a mutation, they must roll a sanity saving throw DC 15. If they fail they gain an Indefinite Madness effect. Once they have failed this check once, they have succumbed to the Dark madness and don't make any further rolls.

Display Cases

These are simple glass cases that can easily be broken. The following is inside the cases:

• Scroll of Endothermic Ray
• Dark Brew x3

Choir Chamber

You step through the door into a long, symmetrical chamber filled with the heavy scent of aged wood and worn upholstery. Rows of red-cushioned benches stretch out before you in two neat columns, divided by a central aisle that leads to another door way directly across the room. The polished wooden benches are sturdy, lined with brass fixtures that gleam dully in the muted lighting. The stone walls and structured symmetry give the place a formal, almost ceremonial feel. The only sounds are the faint echoes of your own footsteps and the distant hum of machinery below the surface, pulsing like a forgotten heartbeat beneath the floor. Light flashes in the darkness as figures step out of the gloom on either side of the door.

There are two Magmin in here. If the party wasn't careful in their approach, they could be surprised. The Magmin have a stealth of 12. Compare this to the character's passive perception scores to see if they notice them hiding in the shadows.

North Entrance

You slip in through the heavy side door, the hinges groaning just enough to send a shiver up your spine. The room you enter is dim, lit only by what light filters through the fractured stained glass above. You find yourself in a narrow antechamber just off the grand cathedral hall—its stone floor cold beneath your boots, scattered with wilted prayer scrolls and broken votive candles. To your right, there is a door. In front of you is the main sanctuary where the pews stretch in solemn rows, but here it feels closer, more intimate. The air carries a strange mix of incense and rot. A toppled statue of a weeping angel lies face-down beside an old confession booth, its wood cracked and darkened with age. You can hear something moving faintly beyond the pillar—a scraping sound, rhythmic and slow. Then it steps out of the shadows. Its body a blackened mass of charred muscle and cracked obsidian-like skin, glowing from within with the relentless heat of eternal fire. Flames pour from its eyes, mouth, and along its spine, licking the air with a furious hunger as molten embers fall in its wake. This creature is no ordinary beast—it is a living inferno born of destruction, its growl like the rumble of a collapsing world

The door on the left hand side is unlocked.

The party can see the first Hell Hound from here, but cannot yet see the second one that is by the other front pillar, next to the stairs to the podium.

North West Chamber

You step into a dim, octagonal chamber, the door sealing shut behind you with a soft hiss. The floor is tiled in a dark, diamond-patterned metal that reflects the faint overhead light in muted glints. A heavy, red-cushioned bench sits directly across the room, framed by angular stone walls that lean inward with subtle menace. To your right stands a tall, armored statue—its blank, imposing face turned slightly toward you, as if aware of your presence. In front of you, a control console rises from the floor, outfitted with two sturdy dials and inset lights that flicker with quiet anticipation. The room is silent, but the air hums with the tension of something waiting to be activated.

Puzzle Scenario:

As the party enters the room, the door locks behind them with a loud clang. Moments later, the control console emits a low tone and powers up, its lights glowing steadily. A screen slides open above the console, revealing glowing text:

“To proceed, you must speak the truth. One statement is false. Choose wisely, or awaken the guardian.”

Beneath this are three statements displayed on the screen:

1. "The statue in this room has never moved."
2. "Only one of these statements is false."
3. "The door will open if you choose the second statement."

How the Puzzle Works:

• The key is logical reasoning.
• If Statement 2 is true (that only one statement is false), then:
• If Statement 1 is true (the statue has never moved), and
• Statement 3 is true (the door opens if you choose statement 2),
  → Then all three statements would be true, which contradicts statement 2.
• Therefore, Statement 2 must be false (which is the twist). That means more than one statement is false.
• If Statement 2 is false, and
• Statement 3 is false (choosing 2 does not open the door), and
• Statement 1 is true (the statue has never moved),
  → Then only one statement is true, which checks out.

Correct Answer: Choose Statement 1 as the true one.

Outcome:

• Correct Choice (Statement 1): The console beeps approvingly, the lights dim, and the door unlocks with a hiss.
• When the door opens, a small compartment in the console also opens, revealing a jar of Bee Pollen.
• Incorrect Choice: The screen goes dark. A grinding noise echoes through the chamber as the statue turns its head—and lunges.

Forward Pews

You step into a long, solemn hall lined with cold stone and shadowed alcoves. Wooden pews stretch down the center in two neat columns, their surfaces worn smooth by time and reverence. Dim light filters in through narrow slits high in the walls, casting thin beams across the tiled floor and the dust that floats silently in the still air. Recessed into the walls on either side are sealed sarcophagi, each adorned with faded carvings and metal inlays—guardians of a forgotten past. The silence here is oppressive, heavy with memory, and each step you take echoes like a trespass in a sacred tomb.

There is nothing of importance here.

Chancel

You step into the crumbling chancel, the stained-glass windows long since shattered, casting shards of sickly light across the scorched stone. At the altar stands a figure—tall, skeletal, wrapped in writhing shadows and charred metal. Its eyes, twin embers of unholy fire, pierce through you with a hunger that speaks of years spent in silence and suffering. Flames flicker at its fingertips, not born of warmth but of rage, casting hellish light across the ruin. The air thickens, vibrating with arcane heat, and the smell of scorched ash claws at your lungs. You know without question: this is no priest, but the god this place now worships.

As an after thought, your mind registers the bear standing to the left of the fiery being. It seems insignificant in the presence of what could only be Ilsa herself.

This is the boss battle. It can be won through combat or by social interaction with Ilsa that leads to convincing her to abandon the cult.

Boss Strategy

Ilsa will attack fiercely. Ursa will remain close to Ilsa and defend her whenever possible to prevent her from taking damage. Ursa will attack on his turn, but not if it means moving in a way that would leave Ilsa exposed. Ursa will die defending her. Ilsa will flee if her hit points drop below half. If Ursa is still up, she will mount him and ride him out of the cathedral. If the party chooses to, they can chase her.

Chase

When a chase begins, determine the starting distance between the quarry and the pursuers. Track the distance between them, and designate the pursuer closest to the quarry as the lead. The lead pursuer might change from round to round.

Running the Chase

Participants in the chase are strongly motivated to take the Dash action every round. Pursuers who stop to cast spells and make attacks run the risk of losing their quarry, and a quarry that doesn’t take the Dash action is likely to be caught.

Dashing

A chase participant can take the Dash action a number of times equal to 3 plus its Constitution modifier (minimum of once). Each additional Dash action it takes during the chase requires the creature to succeed on a DC 10 Constitution saving throw at the end of its turn or gain 1 Exhaustion level. A participant drops out of the chase if it has 5 Exhaustion levels. A creature can remove the Exhaustion levels it gained during the chase by finishing a Short or Long Rest.

Spells and Attacks

A chase participant can make attacks and cast spells against other creatures within range.

Chase participants can’t normally make Opportunity Attacks against each other, since they are all assumed to be moving in the same direction at the same time. However, participants can still be the targets of Opportunity Attacks from creatures not participating in the chase. For example, adventurers who chase a thief past a gang of ruffians might provoke Opportunity Attacks from the ruffians.

Ending a Chase

A chase ends when one side or the other stops, when each quarry escapes, or when the pursuers are close enough to their quarry to catch it.

If neither side gives up the chase, the quarry makes a Dexterity (Stealth) check on Initiative count 0 each round, after every participant in the chase has taken its turn. If the quarry is never out of the lead pursuer’s sight, the check fails automatically. Otherwise, compare the check’s total to the Passive Perception scores of the pursuers. If the quarry consists of multiple creatures, they all make the check separately, so it’s possible for one quarry to escape while others remain in the chase.

The quarry can gain Advantage or Disadvantage on its check based on the circumstances, as shown in the Escape Factors table.

	Escape Factors
Factor	Check Has...
Many things to hide behind	Advantage
A very crowded area	Advantage
Few things to hide behind	Disadvantage
An uncrowded area	Disadvantage

Other factors might help or hinder the quarry’s ability to escape, at your discretion. For example, a quarry with a Faerie Fire spell cast on it might have Disadvantage on checks made to escape because it’s much easier to spot.

If the total of the quarry’s check is greater than the highest Passive Perception score of the pursuers, the quarry escapes. If not, the chase continues for another round. Escape doesn’t necessarily mean the quarry has outpaced its pursuers. For example, in a city, escape might mean the quarry ducked into a crowd or slipped around a corner, leaving no clue as to where it went.

Note: If Ilsa is caught, she will continue to fight them and this time she will fight to the death.

Chase Complications

Unexpected complications make a chase more exciting. The accompanying Urban Chase Complications table and Wilderness Chase Complications table provide several examples. Each participant in the chase rolls 1d12 at the end of its turn. Consult the appropriate table to determine whether a complication occurs. If it does, it affects the next chase participant in the Initiative order, not the participant who rolled the die.

Characters can create their own complications to shake off pursuers or slow their quarry (for example, casting the Web spell in a narrow alleyway). Adjudicate these at your discretion.

	Urban Chase Complications
1d12	Complication
1	A cart or another large obstacle blocks your way. Make a DC 10 Dexterity saving throw to get past the obstacle. On a failed save, the obstacle counts as 10 feet of Difficult Terrain for you.
2	A crowd blocks your way. Make a DC 10 Strength, Dexterity, or Charisma saving throw (your choice) to navigate through the crowd. On a failed save, the crowd counts as 10 feet of Difficult Terrain for you.
3	A maze of barrels, crates, or similar obstacles stands in your way. Make a DC 10 Dexterity or Intelligence saving throw (your choice) to navigate the maze. On a failed save, the maze counts as 10 feet of Difficult Terrain for you.
4	The ground is slippery with rain, spilled oil, or some other liquid. Make a DC 10 Dexterity saving throw. On a failed save, you have the Prone condition.
5	You encounter a brawl in progress. Make a DC 15 Strength, Dexterity, or Charisma saving throw (your choice) to get past the brawlers unimpeded. On a failed save, you take 2d4 Bludgeoning damage, and the brawlers count as 10 feet of Difficult Terrain for you.
6	You must make a sharp turn to avoid colliding with something impassable. Make a DC 10 Dexterity saving throw to navigate the turn. On a failed save, you collide with something hard and take 1d4 Bludgeoning damage.
7–12	There is no complication.

Note: Some of these complications will require some interpretation to make them work in the current setting. A crowd can become a group of animals. A brawl in progress can be fighting animals or fighting zombies.

North East Chamber

You enter a small, dimly lit chamber cloaked in deep shadow, the only illumination a faint gleam from the polished black tiles beneath your feet. At the center of the room rests a wooden coffin atop a raised platform, its surface carved with a simple cross—unadorned, but commanding. Heavy red drapes hang along the angled east wall, their folds motionless yet somehow watching. To your left a tapestry hangs on the western wall, faded and thread bare. It's difficult to make out what it once depicted. On the northern wall, old boxes slowly crumble to dust, revealing the faded fabrics that they contained.

There is nothing important in here.

South East Chamber

You step into a narrow, angular chamber where the scent of dust and parchment hangs heavy in the air. Dark tiled floors stretch beneath your feet, their pattern stark against the pale stone walls. Three ornate display cases rest in the room—one to your immediate left on the northern wall, another set at a slant along the eastern wall, and a third against the south wall. The cases suggest a reverence not just for the items, but for the knowledge or legacy they represented. A tapestry hangs on the western wall. It is worn and thread bare, but you can still see there is a man in the center of the image holding a large blue orb in his hands. The quiet here is not oppressive but contemplative, as though you’ve stepped into a crypt built not for mourning, but for remembering.

In the display case against the Northern wall, there are 4 well preserved books. Three of them are clearly religious books, but the last one seems to be something different. It is a thin volume, hand written in careful English. It speaks of people changing and a darkness settling over the world. They speak of revelations and a testing of faith. Within the book, there are three spells transcribed into the pages. These can be used in the same manner as scrolls.

Table of Contents

Click on a heading to go to that section

The Oath Ash does not forgive—it remembers. Every vow broken, every promise scorched away by cowardice, it holds within itself. Step into its circle, and know what you truly are.

— Ilsa Var

Type

Temple / Church

Characters in Location

• Ancient Construct
• Hell Hound
• Ilsa Var
• Magmin
• Ursa

Bypassing Locked Doors

There are several doors that are locked in this facility. Those can be bypassed with the standard rules with either lock picking of electronic locks or by breaking down metal doors. Those rules can be found in the Scavenging Rules. These can also be used to flesh out the scavenging of the facility.

Breaking the Containment Unit

The Containment unit has AC 19 and 10 hit points

A Strength check can model any attempt to lift, push, pull, or break something, to force your body through a space, or to otherwise apply brute force to a situation. The Athletics skill reflects aptitude in certain kinds of Strength checks. Generally, when by passing a mechincal lock or type of obstacle within this category, you will be rolling a strength check rather than an athletics check. If you'd like to have athletics apply, you will need to explain what action you are taking, keeping in mind the above check guidance.

An object’s Armor Class is a measure of how difficult it is to deal damage to the object when striking it (because the object has no chance of dodging out of the way). See the table below for suggested armor classes for objects.

An object’s hit points measure how much damage it can take before losing its structural integrity. Resilient objects have more hit points than fragile ones. Large objects also tend to have more hit points than small ones, unless breaking a small part of the object is just as effective as breaking the whole thing. See the table below for suggested hit point for objects.

Objects are immune to poison and psychic damage. The GM might decide that some damage types are more effective against a particular object or substance than others. For example, bludgeoning damage works well for smashing things but not for cutting through rope or leather. Paper or cloth objects might be vulnerable to fire and lightning damage. A pick can chip away stone but can’t effectively cut down a tree.

This journal is no ordinary book, but rather a magical item. If a character reads through the entire journal, they become effected by the magic of the book. They must roll a sanity saving throw DC 10. Failing results in them succumbing to an indefinite madness effect. Whether they pass or fail the save, their Vigor score becomes 12. This has no effect if their score is already 12 or higher (but they still must roll the sanity saving throw).

As you close the fragile cover of the journal, a sudden hush descends—deeper than silence, as though the very air is holding its breath. The last words still echo in your mind, but something else stirs beneath them, a whisper not heard with ears but felt along your spine. A warmth blooms in your chest, slow and steady at first, then sharp, like a coal pressed into flesh. Shadows at the edge of the room seem to lean closer, as if listening. Your breath catches. The world does not look different—yet feels irreversibly changed. Thoughts not your own coil at the edge of your mind. You know things now—fragments of ritual, flickers of sight into what lies hidden, the shape of a name that does not belong in any holy book. It is not light that awakens in you. It is something older. Something waiting. Something that dwells within the Dark.

Surrounding Area

The area around the Cathedral isn't really part of the adventure. However, it can be used as a scavenging location or if desired, it can become an extension of the adventure by dropping in random encounters. The areas can be seeded with any lore items that the party missed in the cathedral itself, rewarding them for spending more time in the area.