As careful listeners of the Oasis Down and Memory Grove one-shots have surmised, I have been slowly developing my own campaign setting. I frequently see advice online that campaign planning begins with a map. While I love maps of all shapes and sizes, I decided that was not how I wanted to start with this world. Everytime I sat down with a pen or map making software, I found myself unhappy with the results. The borders between lands, the geography and trade routes, all this is important, but I know that my player characters will only ever see them from an “ant’s eye” view. My players, their allies, even the gods of the world don’t have a strong understanding of the world map, why must I? Of course there are deserts and jungles and metropolises and little villages, but no one really knows what is beyond the horizon unless they go there. There may be regional maps, but no one has stitched them all together in a helpful (or comprehensive) way.

What is important to me instead is the following:

1. The themes of the world. Ideas and concepts I want to come out in play.
2. The mythology and mystery of the world. Things player characters are going to want to dive into, pick apart and contribute to.
3. The motivations of the major players. The NPCs and Big Bad Evil Guys and what makes them tick.

What I tell the players:

1. This world is wild and untamed, with points of civilization and humanity few and far between. Vast tracts of desert, jungle, mountain or sea hide the histories of forgotten cities and civilizations that have come before. In this world, a number of mortals have achieved “Ascendancy.” That is to say, they have garnered enough power, followers and infamy to have become legendary and powerful demigods that roam the world, establishing dominion over others. They are without question the most powerful beings around and gods as you know them in other settings do not exist here. Either they have fled, been killed, or been abandoned themselves by their former followers.
   • If we’re playing 5th edition, Clerics and Warlocks derive their powers directly from these beings, either by worshipping the ideals of the Ascendant and gaining divine power in the case of clerics, or by striking a direct bargain with an Ascendant or another Warlock acting as an agent of that demigod in the case of warlocks. (I adapt this system when we play using systems like Pathfinder, Dungeon World, or whatever else).
2. There are not countries or nations, but instead small kingdoms, cities or armies that hold out a place amongst the rubble of the world. Some are led by Ascendants, some are led by more common folk that refuse to bow to the demigods.
3. There are many mysterious happenings in the world that have come about through the direct or indirect actions of these demigods, and that is what adventure in this world revolves around.

So far my campaign has been enjoyed privately via a small home campaign that was 8 or 10 sessions, and a few one shots, some of which you’ve heard on our podcast. I most often think about adventures for this campaign setting as one shots; they are easier to plan for, and I can make each adventure a strong thematic tie in to the main concepts of my campaign world.

Usually I think about movies or shows to draw inspiration from. This time I’m thinking about a particular location: the middle of the ocean. The players and a set of NPCs, all with different motives and mysteries, become stranded on a platform in the middle of the ocean. Add a ticking clock that the PCs have to outrun and baby, you’ve got a stew going.

Prepping the session

I know that for this session I want a mix of Crime Scene Investigation and Aliens 3. The themes and feelings I want to draw out are: paranoia, suspicion, dread. I want players to have to investigate, interrogate, argue and confront. I don’t want the investigation to immediately cascade into a running battle to death. There needs to be something of value, volatile enough that both allies and enemies are careful not to tip the scale, resulting in the ruin of everyone on board. To that end, I’ve come up with a location, a poison, a magical item and a monster I can challenge my players with. 

Location – The Saltstack

A large platform on stilts, mount on submerged foundations in the roiling sea. The platform sits 60 feet above the surface of the water, the legs extending down more than a hundred feet to the seafloor. On the platform is a large three story building, a blend between cabin and factory. It is home to the 9 or 10 crew members that maintain and run the Extractor. The Extractor is a magical engine connected to a 4 foot diameter glass tube that extends from the basement of the factory pierces the seafloor, and acts as a vacuum tube to extract precious materials from submerged heat vents. Operating the Extractor requires two spellcasters to work in concert, expending their daily spell slots to power its pumps. Manna Sludge is vacuumed from the sea floor, deposited into vats and then sifted, separated, and dried by the rest of the crew. Due to the dangerous nature of the work and the humidity in the area, the processing of Manna Sludge into Manna Dust is a slow process, but its extraordinary value as a spellcasting component makes it a worthwhile venture.

Poison – Brainslug Scum (Ingested)

This gooey ooze contains a mass of diminutive plankton like creatures that when ingested, work their way into the nervous system of the host, subjecting the victim to excruciating pain before taking control of its brain and motor functions. The brainslug scum is used by aquatic creatures to plant sleeper agents and spies among their enemies on land.

A creature subjected to this substance must make a DC 15 Constitution saving throw or become infected by brainslugs. The victim becomes poisoned as the slugs begin to latch onto the host’s nervous system. After 2d4 hours of infection the victim must make a second DC 15 Constitution saving throw or succumb to the brainslug’s mind control. The host’s personality becomes supplanted and assimilated into the slug’s. An observer can note the host’s behaviour as bizarre or out of character with a DC 18 Insight check. If the observer is very familiar with the host, the Insight check is made with advantage.

Item – Manna Sludge, uncommon

This thick black sludge harvested from heat radiating vents beneath the ocean’s surface serves as a powerful enhancement to arcane magical components. Once dried and powdered, the manna is stored in a small watertight pouch and can be used as a replacement for any material component required for arcane evocation spells. The more manna imbued into the casting of a spell, the more powerful its effects.

When casting a spell of the evocation school, a caster may expend a pouch of manna to choose one of the following: double the range of the spell (touch spells are unaffected), increase the area of effect by 50%, or deal damage as if the spell were cast from a spell slot two levels higher. By expending additional pouches of manna, the caster can choose more than one option, but cannot select the same improvement twice.

Manna Sludge and powder is volatile. If a pouch is exposed to magical fire, it combusts explosively, dealing 2d6 fire damage to anyone or anything that shares a square with the manna. All creatures adjacent to the explosion must make a DC 13 Dexterity save or take 1d6 fire damage. Anyone carrying manna on their person in any form must make a DC 10 Dexterity save any time they take fire damage to protect the manna from exploding. Larger quantities of sludge or powder are significantly more dangerous.

Monster – Slugmorph

Brainslugs are a special breed of aquatic creature, suited for life within the bodies of stronger creatures. Normally this keeps the brainslugs themselves safe from harm. When an infected host is exposed to the powerful energies of the Manna sludge, brainslugs undergo a dramatic transformation, growing exponentially, bursting from the pores of the host’s body, but still driving the musculature and nervous structure. A slugmorph is a frantic, pain driven machine of death. It cannot be reasoned with as it lashes about at anything it perceives, be it creature or object.

Where to go from here?

With the setting, a monster, the literal bomb in the room and a blank slate of characters on board, this adventure could now take any number of forms. I have an idea of where I would take it, but what about you?

• Are the PCs members of the crew, working diligently and waiting for the weather to clear before their shift ends and a new crew arrives?
• Are they a delegation from a general that wants the Saltstack inspected and – if everything is up to snuff – a deal for exclusive buying rights drawn up?
• Is the brainslug infection an accidental occurrence … or is a subaquatic intelligence taking the harvesting of Manna Sludge as an act of aggression?
• Does a life raft wash up to the rig bearing a survivor of a shipwreck? They come with tales of terrifying sea creatures and brainwashed crewmen, filling the Saltstack’s workers with fear.