• Adapted from the Cairn Adventurer’s Guide Adam Hensley, used with permission.
  • This content is licensed under CC-BY-SA 4.0
  • This document lists some optional, modularly-designed rules & procedures for Cairn (and should be adaptable to most other OSR-adjacent games with minimal tinkering).
  • These rules are designed to be plug-n-play. Grab what you like and discard the rest.
  • These rules are not critical to the structure of the game and can be discarded or ignored at certain points in your game.

Table of Contents

Dungeon Exploration

Dungeon Turns

A dungeon turn is approximately 10 minutes. Dungeon exploration can be turned into a subsystem of managing resources, making strategic decisions, and structuring the dungeon crawl into a sort of mini-game. There is an element of pushing your luck as you spend more time searching, checking for hidden things, and lingering in dangerous locations. Time spent always has a cost, and that cost is provoking an encounter roll. These encounters can involve running into monsters, but can also challenge or reward the party in other ways.

Sequence of Player Per Turn

1. Encounter Roll: GM makes a d6 loaded encounter roll once every few dungeon turns, or at their discretion.
2. Actions: The party decides what action to take. (e.g. moving, searching, listening, entering or exiting rooms).
3. Description: GM describes & resolves what happens. If encounters were rolled, they happen here. If (1) was rolled on the encounter die, make a reaction roll and proceed from there.
4. End of turn: GM updates time, and management of light, food, need to rest, or any sort of usage dice rolls can be made.

Dungeon Turn Movement

Players can move carefully about 200 ft. in a 10 minute turn. Players moving carefully spot signs of all traps. Traps should be designed to be disarmed or subverted with ingenuity and creative thinking using common sense and inventory. Players can quickly move 600 ft. in a 10-minute turn. Players moving quickly may get a chance to roll under WIL to notice a trap (GM discretion). Otherwise, they may trigger a trap if it is concealed (usually 1-2 on a d6, adjust as necessary for trap deadliness).


  • A quick search takes 1 minute, covers roughly a 30x30’ space, and reveals only the most obvious information.
  • A detailed search takes 10 minutes (1 turn), covers roughly a 30x30’ space, and reveals most hidden information.
  • You can replace 30x30 with small, medium, and large rooms, and require additional turns to complete a detailed search.

Loaded Encounter Roll

  • Roll a d6 encounter dice every 2 or 3 rounds (at your discretion, adjust as needed) or when players make noise.
  • Only a roll of 1 will result in an encounter, and they won’t always be hostile.
  • Roll the reaction dice to see their disposition, and remember that they’re already doing something.
  • Optionally, you can roll non-loaded encounters with only and encounter occurring on a roll of 1, while nothing else happens otherwise.

1. Encounter (roll on encounter table or choose, roll reactions + wants)
2. Sign (Clue, “spoor”, track, abandoned lair, scent, victim, droppings, etc.)
3. Locality (context-dependent timer, water rising, ritual completing, The party’s surroundings shift or escalate in some way.)
4. Exhaustion (rest next round or deprived)
5. Expiration (Ongoing effects end, light usage roll, resource usage, bellies rumble.)
6. Discovery or Treasure (The party finds something interesting and possibly beneficial.)


Torches, lanterns, and other radial sources of light illuminate 40’ clearly and provide dim outlines and shadows for a further 40’. In the dark, light sources are visible miles away. Standard torches will last about 6 turns, or 1 hour, before they burn out.

Wilderness Exploration

Hex Crawling

Each hex represents 6 miles. An adventuring day is divided into 6 turns of approximately 4 hours each. Two of these phases, approximately 8 hours, must be spent sleeping in order to avoid becoming deprived. In each turn, the following procedure is followed:
1. Exploration Action: The party decides on one exploration action for that turn.
2. Event Roll: The GM rolls on the event die for encounters and other random events.
3. Resolution: The action and event rolls are resolved.

Wilderness Exploration Actions

The party may choose one of the following standard actions each 4-hour wilderness turn.

  • Travel: Exiting a hex and moving into an adjacent one.
  • Roads: The party travels through two tiles (three if mounted).
  • Standard Terrain: 1 tile is traversed.
  • Difficult Terrain: ½ tile is traversed. (requires 8 hours, or 2 turns)
  • Treacherous Terrain: ¼ tile is traversed. (requires 16 hours, or 4 turns)
  • Getting Lost: There is a 1-in-6 chance, when traveling off-road, of getting lost. This is increased to 2-in-6 in tiles classified as difficult or treacherous. An experienced woodsman or explorer decreases the chance of getting lost by 1-in-6.
  • Off-Course: When lost, assign a number to each adjacent tile starting from the top (north) as 1, continuing clockwise. Roll 1d6 and move the players one tile off-course that direction.
  • Reorientation: If players get lost, they will need to spend the next turn reorienting themselves.
  • Weather: Adverse weather can optionally increase the chances of getting lost or the difficulty of the terrain.
  • Explore: Looking for interesting features within a hex. There is a 4-in-6 chance of discovering the main location in the hex description. Difficult terrain reduces this to 3-in-6. An experienced woodsman increases the chance by 1-in-6.
  • Locate: Looking for something which was previously encountered in a hex. The basic chance is 5-in-6 or 4-in-6 in difficult terrain. An experienced woodsman, tracker, or navigator increases the chance by 1-in-6.
  • Interact: Staying in the current location (e.g. exploring a dungeon, town, etc).
  • Camp: Resting and/or sleeping.
  • Forage: Hunt, fish, or forage for food. There is a basic 3-in-6 chance of success. An experienced hunter, angler, or woodsman increases the chance.

Event Roll

The GM rolls a d6 and consults the table appropriate to the party’s location.

1. Encounter: Roll on an encounter table for that terrain type or location. Don’t forget to roll for reaction and want.
2. Sign: Clue, spoor, or indication of nearby encounter, locality, hidden feature, or information about a nearby hex.
3. Locality: Shifts in weather, terrain, or other local changes.
4. Expiration: Resources are drained in some way. Roll a d4.

  • 1-2: Exhaustion (rest for a turn or add 1 fatigue)
  • 3-4: Hunger (Eat a ration or add 1 fatigue)

5. Discovery: Discover something useful such as food, treasure, or other resources.
6. Hidden Feature: The main feature of the hex is discovered, or, choose or roll randomly for a unique hex feature from a random table. Options include small dungeons, secret areas, factions, etc. If none apply, this result is simply a free turn.


When the PCs encounter an NPC whose reaction to the party is not obvious, the Warden may roll 2d6 and consult the following table.

2 3-5 6-8 9-11 12
Hostile Wary Curious Friendly Helpful

What Do They Want?

Most NPCs will have something they want. Roll a d10 on the following table to find out what they want.

d10 Want Description
1 Food You can distract them with rations, point them towards corpses, cast a food illusion.
2 Aid They could be hurt and need medical aid of some sort.
3 Gold They want money. Extortion, toll, tax, tribute, or greed.
4 Valuables Rare or unique items. Excellent pairings can result in their friendship or gaining as allies.
5 Territory This is their turf. They will defend it, ask you to leave, or to prove why you should be able to pass through.
6 Info They want to know about a nearby NPC, faction, landmark, or location.
7 Help They need something from nearby, probably somewhere dangerous. Kill something, clear out an area, retrieve something.
8 Trade They have random equipment (from each category on the equipment tables) and want to trade or sell. 1 in 6 chance they have something rare or valuable. Good business means possible friendship.
9 Mission They’re in service to another nearby NPC or faction and are helping to achieve a goal for them.
10 Directions They are lost and need directions somewhere, or help being escorted there safely.

Leveling Up

Experience Points (XP)

Gain a new level every 1,000 XP. Optionally increase the XP needed each level. A good place to start is adding between 500-1,000 XP each level.

Gaining XP

Experience points are gained at a rate of 1 XP for every 1 gold (or your game’s standard currency) retrieved and returned to the safety of a town or your base of operations.

Increasing HP & Ability Scores

Each time you level up:

  • Roll 1d6 and add to your HP total.
  • Re-roll each Ability Score with 3d6. If a result is higher than your current score, increase that Ability Score by 1.


You can spend your hard-earned credit on experiences rather than on things. Carousing lets you double-dip your experience by spending it at a 1-1 ratio. The more you spend, the more impactful or eventful your experience. Carousing represents having a good time, donating your money, investing in a “business opportunity”, or some other experience involving your wealth and blowing off steam. Alter these tables or add your own mishaps and fortunes. They generally represent getting into shenanigans while inebriated but can also be sober celebratory outcomes.

Carousing Roll

Declare the amount of gold you’re spending and roll 2d6 to see how your evening went.

2d6 How Things Went
2-5 Mishap: Experience is gained, but you’ve all made fools of yourself in some manner. Roll on the carousing mishaps table.
6-9 Responsible Time: Experience is gained and you all kept things reasonably sane.
10+ Fortune: Experience is gained, and you’ve all had a stroke of good luck! Roll on the carousing fortunes table.

Mishaps & Fortunes Table

  • Roll 1d6, adding + 1 to the results for every 100 GP you carouse with. Larger cities should allow for (or require) more money to be spent. More decadent partying comes with the potential of more volatile or legendary consequences.
  • Alternatively, just roll a 1d12 and check the results.
d6/d12 Mishaps Fortunes
1 Start a brawl. You all are involved in a brawl that gets out of control. Start the next adventure with a black eye and -1 STR per level. The local tavern keeper is no longer quite as amicable. Jackpot! One of you strikes it rich at the gambling tables! Gain level x 100 gold. (Or 1D6 x 100 if playing without levels)
2 Minor misunderstanding with local authorities that you’re unable to smooth over. You all spend the next 1d6 days in jail. Now seen as local troublemakers. Gain a local reputation as the life of a party! Those of ill repute are much more friendly and see you as one of their own.
3 One of you insulted a local person of rank. They will hold a grudge unless you all publicly apologize and humiliate yourself before them. Whoa what a trip! The strange powder you sniffed revealed mystic truths about the universe. Young people in the settlement see you as cool and not one of the squares. (Optional: gain a random spell or generate a Maze Rats spell, either one-use or permanent.)
4 Hangover from hell. The first 2d6 hours adventuring the next day are done with disadvantage to all STR saves. Well fed, well rested, and ready to go! The next day of adventuring all saves are done with advantage.
5 Gambling binge. Your party owes a collective debt equal to roughly half the amount spent carousing to someone you’d rather not own money to. Citizens arrest! You catch some criminal in the act and are able to restrain them until the authorities arrive. You are seen as hero’s by the settlement for a short time.
6 You’ve ruined the local economy! Your excess spending means that all prices are now double until next session. The local blacksmith, due to your influx of cash, has been able to order in an exquisite weapon that he’s willing to sell to you guys for the normal price.
7 Major misunderstanding with local authorities. All equipment is confiscated until fines and bribes totaling 1d6 x 100 gold is paid. The local clergy see you guys as protectors of the settlement. They offer you a blessing before your next adventure.
8 While in a drunken stupor and a spot of trouble, you sought refuge in a church. They took care of you but now as repayment have begun hounding you to perform a charitable act. Impressed by your ability to drink for days and keep standing, a local hireling of high repute is willing to join you on your next adventure if you wish at no initial cost.
9 Bad Investment. Invest all your spare coin in some smooth-tongued merchant’s scheme. Turns out it’s a sham. One of the towns merchants flees. Killer Investment! Invest all your spare cash in some smooth-tongued merchant’s scheme. Turns out it’s real! It returns 50% profits next d4 sessions.
10 Due to a lost game of darts and a few inflammatory remarks at the tavern, you make bitter enemies with a local rival adventuring party. Local celebrity. Your ability to carouse with the common folk as lead them to see you as one of their own. The peasants of the settlement are thankful to have you around. You receive free room and board in this settlement of poor quality.
11 Beaten and robbed. You are waylaid by a bunch of thugs during your drunken carousing. Collectively lose L6d100 coins. Hot Goss. Your time spent carousing has let you in on some juicy gossip. You learn one major secret about a person in authority.
12 The roof! The roof! The roof is on fire! Accidentally start a conflagration Roll 1d6 twice. (1-2) burn down your favorite inn (3-5) some other den of ill repute is reduced to ash (6) a big chunk of town goes up in smoke. (1-2) no one knows it was you guys (3-5) one other person knows you did it (6) everybody knows. Heroic Carousing! It was a night of truly epic debauchery. Everyone roll a d6 to see how your legend grew. (1) Re-roll HP for that level, take new result if higher, increase by 1 if lower. (2) Gain 1 STR (3) Gain 1 DEX (4) Gain 1 WIL, (5) Gain a random spell book (6) Gain Ld6 x 100 GP.


Vices serve as both character growth and a way to pressure PC’s pockets and keep them continuing to adventure & acquire wealth to support their vice. If PCs start out with a group debt, a vice is a nice way to continue bleeding their wealth after they pay off their debt.

Gaining Vices

Players can roll for a vice during character creation, or acquire one through the fiction of play. Roll a D10 for a random vice. Otherwise, consult the triggers for suggestions on what might trigger a character to develop a vice. You can require them failing a WIL save after hitting a trigger if you wish. Alternatively they can willingly take on a vice they find interesting.

Satisfying Vices

Vices must be appeased once a week or the PC must pass a WIL save. Failing a WIL save adds the deprived condition until they satisfy their vice. Appeasing a vice should cost money in some way, whether directly from money or indirectly via resources.

1. Gambling Playing cards, throwing dice, or other forms of risking money to games of chance.

  • Triggers: A major win or loss at a high stakes gambling game.
  • Satisfying: Gamble with at least 10% of your personal wealth, wager a unique, useful, or powerful item, or put other significant stakes on the line.

2. Alcohol Drinking ale, wine, spirits, or other alcoholic beverages that intoxicate your senses

  • Triggers: Consuming large amount of booze, heavily drinking multiple days
  • Satisfying: Binging heavily, drinking while buying rounds for the whole tavern, brewing your own alcohol.

3. Drugs Narcotic delights to smoke, snort, or consume in search of oblivion.

  • Triggers: Indulging in addictive substances, unwilling exposure to narcotics, overuse of potions or magical alchemy.
  • Satisfying: Overindulging in your particular addiction.

4. Lust Pleasures of the flesh, such as dalliance with strangers or visits to paid workers.

  • Triggers: Regular visits to brothers, unique or novel intimate experiences.
  • Indulging with new partners, frequent copulation, finding lustful or kinky novelties.

5. Luxury Expensive clothing, decadent food, art, and general opulence.

  • Triggers: Experiencing decadence, gaining massive wealth in the form of rare treasure.
  • Satisfying: Blowing your money on ostentatious displays of wealth, buying new expensive clothing, food, art, etc. Patronage of an artist.

6. Weird Consorting with devils, contacting unknown entities, and performing forgotten or forbidden rituals.

  • Triggers: Exposure to forces beyond your comprehension, seeking out secrets not meant for mortal minds, cursed items.
  • Satisfying: Discovering new forbidden knowledge or magic, growing weirder, deepening your connection with unknown powers. Expensive materials, sacrifices, or dealings that cost the player money.

7. Obligation Devotion to a cause, organization, charity, or family.

  • Triggers: Experiencing the charity or aid of an organization or cause, supporting a friend or family member through difficulty, strong sense of duty.
  • Satisfying: Supporting your obligation through dues 0r financial assistance.

8. Violence Spectating extreme violence or participating in the bloodshed yourself.

  • Triggers: Regularly spectating or participating in extreme violence or bloodsport.
  • Watch or place bets on bloodsports, participate in arena combat, commit and act of extreme violence.

9. Faith Dedication to a power, deity, ancestry, or other belief system.

  • Triggers: Close encounter with a supernatural being, near death experience, discovering something faith-related about your past.
  • Satisfying: Paying tribute in the form of tithe, sacrifices with expensive materials, donation to a cause.

10. Ambition Pursuing a personal goal, vendetta, or personal project.

  • Triggers: Developing an ambition through observation or experience. Building a keep, an army, attaining status
  • Satisfying: Significant progress toward your ambition via money.

Advanced Combat Options

Weapon Traits

Below are some optional traits a magical or good quality weapon might have. Sweep, parry, and reach are traits any weapon of that type can have. Any of the other traits should be limited to 1 per rare, special, or magic weapon.

  • Sweep: (2 handed weapons only) Make a second attack against an enemy within reach if you roll for maximum damage or your attack reduces the targets HP to zero or lower.
  • Parry: (swords & daggers only) Melee damage of 1-2 is harmlessly parried away.
  • Reach: (polearms only) When attacked with a melee weapon without reach, the attacker must roll half or higher on their damage roll or else you get to attack them first.
  • Enchanted: (magic weapons) Damage ignores armor.
  • Brutal: (magic bludgeoning weapons; 2h only) Critical Damage resulting from a Damage roll of 8 or more from this weapon is an instant kill, and forces a morale Save on the enemy.
  • Deadly: (magic weapons; rare) Re-roll on max damage and add to total.
  • Vorpal: (magic blades; rare) Damage immediately bypasses HP, going straight to STR and requiring a save against Critical Damage
  • Blood-Thirsty: (cursed magic weapons; rare) On max damage, upgrade dice type. 6>8>10. 10 on a d10 will reset the weapon to its base dice and the weapon will need 2d6 hours to recharge. Should have some type of curse or drawback.

Shield Splintering

Players can opt to absorb all damage and effects from an attack in exchange for their shield breaking.

Magic Damage Types

Below are some magic weapon damage types other than +1 damage. Magic damage type on a weapon should lower it’s damage by 1 dice size to account for the extra effect.

  • Cold: On a hit, target makes a STR save or next attack is impaired.
  • Thunder: On a hit, target makes a DEX save or can’t move next round.
  • Necrotic: On a hit, target makes a WIL save or loses next turn.
  • Poison: On a hit, target makes a STR save or 1d4 damage for 1d4 rounds.
  • Disintegration: On a hit, target makes a DEX save vs instant obliteration & the wielder takes 1 fatigue. Exceptionally powerful & rare.

Special Materials

Most weapons will be made from steel. Some special weapons, however, could potentially come from different materials. Consider making a weapon of a special material one dice size less to compensate for its advantages.

  • Cold-Iron: Heavy and prone to breaking. Enhanced vs. fey.
  • Silver: Expensive. Enhanced vs. undead & certain monsters.
  • Mithril: Elven alloy. Silvery-gold. Enhanced vs. goblins.
  • Orichalcum: Dwarven alloy. Deep red-bronze. Enhanced vs. undead.
  • Electrum: Magically forged alloy. Green-gold. Enhanced vs. demons.
  • Meteor Ore: Rare star metal. Multi-hued. Enhanced vs. dragons.

Credits & Inspiration