I think the easiest way to take CARCOSA for a spin is to drop your current campaign into it for a session or three. That weird teleporter at the bottom of the dungeon, a lich with a dimension door spell, a curse… get your players there however you like. They explore a little, get a sense of the unique style & flavor of the setting, and then you can all talk about whether it’s something you might like to dive into as a full campaign.

This is the first of a handful of posts that will offer suggestions about how to port over spells, magic items, demi-humans, etc. I think you might burn players on the setting right off the bat if you yank away all their shiny toys and abilities, so these suggestions offer a compromise that lets them keep their spells & loot but puts a little CARCOSA spin on the situation. None of this is play-tested so if these ideas turn out to be stupid there’s no one to blame but me, and I don’t really give a crap.


The Old Ones dominate CARCOSA and the other Gods of the multiverse aren’t too keen on intruding. Cleric spells have a base 50% chance of failure, modified downward by 5% per level of the caster (ex. a 3rd level Cleric has a 35% chance of failure, an 8th level Cleric has a 10% chance of failure, at 10th level and above the chance of failure is removed). A failed spell counts as spent.

Clerics can turn Cannibals (as Ghouls), Robots (as undead with equivalent HD), and Mummies (as Mummies). Mummy Brains cannot be turned. Space Aliens that witness a Cleric turn a Robot must save vs. spells or suffer an effect identical to an insanity weapon.

Praying for spells can be dangerous and calls to distant Gods are prone to attract unwelcome attention. Total the spell levels requested during prayer; if that number or less is rolled on percentile dice, then roll 1d10 on the following chart:

  1. Azathoth. Waves of howling insanity batter the Cleric’s mind; stunned for 1-4 hours and no spells that day.
  2. Cthugah. The Cleric burns with the intensity of the Old One’s immolating gaze; suffer 1-8 damage, save vs. spells to gain spells for the day.
  3. Cthulhu. Cleric suffers insanity weapon effect for 4-24 hours (no save), no spells that day.
  4. Forsaken. The Cleric’s deity is aghast that its servant is on CARCOSA. No spells until some act of atonement is performed.
  5. Hastur. The Great Old One briefly peers out from the Cleric’s combusting eyes; any who make eye contact are stunned for 1-10 rounds (no save), Cleric blinded for 1-6 hours, when recovered save vs. spells to gain spells for the day.
  6. I’thaqua. Gain spells as normal. For the next 6 days the weather turns increasingly cold & wintry. On the seventh day a frigid cyclone of epic intensity descends upon the Cleric; amid the raging winds and scouring ice, a coven of 4-16 Cultists (Yellow men clad in light grey garments) attack the Cleric and companions.
  7. Nyarlathotep. Gain spells as normal. Stalked by 2 Mummies that attack 2-8 days later.
  8. Shub-Niggurath. Gain spells as normal. A random Spawn attacks each of the next 1-10 days.
  9. Space Aliens. Gain spells as normal. 3-12 Space Aliens attempt abduction during next rest period.
  10. Yog-Sothoth. Prayer interrupted by 1-3 Spawn of Yog-Sothoth, that teleport in and attempt invisible tentacle rape of Cleric; no spells that day.

Ex. a 6th level Cleric prays for his/her full complement of spells: 2 1st, 2 2nd, a 3rd, and a 4th. That totals up to 13 levels of spells requested, which means a 13% chance that something really shitty happens.

Clerics seen casting spells will typically be presumed demonic or sorcerous and treated appropriately; best case scenario, they are only viewed as mutants. This may lead to scenarios in which Clerics are treated as divine, feared and obeyed, or hunted and slaughtered. Sorcerers will take particular interest and be keen to decipher the mystery of any newcomers.

Additional notes, per spell:

Bless: Works as advertised. Reverse: Curse should be yucky and CARCOSA-themed.

Commune: 75% chance the spell is intercepted by a local dread entity; maybe it pretends to be the caster’s god, maybe it gives false answers, maybe it puts in a personal appearance…

Continual Light: Roll randomly to determine color of light (white, green, dolm, orange, etc.). Black equals UV light. Some colors are more useful than others. Reverse: 50% chance of casting Darkness, 50% instead call down a portion of the interstellar void, any within suffer 3-24hp cold damage per round.

Create Food: Local foods may not be palatable (i.e. fungus steaks, slug stew, tentacle pie, etc.).

Create Water: Creates normal, though unmistakably weird water.

Cure Disease: Effective against Diseased Guardians, bizarre sorcerous diseases, certain mutations. Reverse: Inflicts the Diseased Guardian disease.

Cure Light Wounds: If using CARCOSA dice rules, this spell heals 1HD of damage. In any case, 10% chance per hp healed that recipient also suffers a random mutation; save vs. spells each following day, success indicates mutation fades away. Reverse: Very effective, double damage.

Cure Serious Wounds: If using CARCOSA dice rules, this spell heals 2-3HD of damage. Mutation rules as above. Reverse: Very effective, double damage and caster will be the envy of local Sorcerers.

Detect Evil: ‘Evil’ on CARCOSA is relative, DM use judgment when determining effectiveness; in cases with any uncertainty, spell is ineffective. Reverse: ‘Good’ is also relative…

Detect Magic: Sorcery counts as magic.

Dispel Evil: See Detect Evil above.

Find Traps: Yep, still finds traps.

Hold Person: Ineffective against Bone men, for some reason.

Insect Plague: 90% chance that 1d4 random insectoid Spawn show up also.

Light: See Continual Light above.

Locate Object: Can this spell be weirded out? I’m drawing a blank… Tracking things down is so crucial to the setting, this could be a very handy spell.

Neutralize Poison: Cleric lays hands and withdraws poison into his/her own body; can discharge venom in a single spittle attack (up to 10′ range).

Protection from Evil: See Detect Evil above.

Protection from Evil, 10′ Radius: See Detect Evil above.

Purify Food & Water: Works just fine. Reverse: Still fine, but now you’re an asshole.

Quest: Works, and caster will be pestered by local Sorcerers for secret of casting this spell.

Raise Dead: 75% chance a random Old One takes a personal interest in the caster and the recipient: expect minions galore bent on capturing and examining both. Reverse: Local lawful-types will declare war.

Remove Curse: Works as advertised, also cures Diseased Guardian disease.

Speak with Animals: Works with all Spawn.

Speak with Plants: Lotus plants are devious, lying bastards. Also works with non-intelligent plant Spawn.

Turn Sticks to Snakes: Not snakes, squirmy semi-intelligent 1HD tentacles instead that have a fondness for penetrating victim’s orifices. Once the target is dispatched they will turn on the next nearest victim (including caster and friends).