This is a hack that evolved organically from a hobby project to convert the Dungeons and Dragons Curse of Strahd board game into a prototype for a random dungeon deck using a standard deck of playing cards. I used 5e but it could easily be system agnostic.

The idea is simple, each card represents an encounter or encounter modifier of some sort.  You can play theater of the mind or setup each encounter on a mat or with tiles, however you might typically do things. However, the cards allow a interesting middle ground, you can actually lay them out in the shape of the dungeon regardless of how you execute combat, as sort of a strategic layer map. Almost like you’d see in a video game. This removes the need to sketch out the entire dungeon and you can just use your mat, tiles or board to map a single room at a time.

I use the suits as a thematic reference, face cards to generate more significant events. Black suits are bad, red are good. The Ace or King of Spades will typically be a boss and mini-boss encounter. Hearts control the short and long rest opportunities. You can shuffle those into the lower portion of the deck from the start or discard rest cards to shuffle any encounter back in. Face cards for other encounters might be treasure hoards or good NPC encounters. You can use the jokers as party level ups for milestone leveling or just remove them and count XP.

To generate the dungeon spatially with the cards you simply connect the cards long edge to short edge as you draw them. Each card-room has d4 doors, 1 meaning the door you came through. 2 meaning 1 additional door attached to any side you choose however it must not connect back to another room if you can help it.  If you roll 4 each side of the card has a door. To represent each door secretly place a card face down to represent the new rooms and their hidden contents.

To Scale encounters I like to use a character count modifier represented by “C”. For example: Skeletons Cd6. This means roll a d6 for each character in the dungeon (even if the party is split). 

Here’s an quick example deck Its roughly set for a group of 4 characters around level 5, it scales a some for character count but is not fair for a single character, “its dangerous to go alone”. C is short for Character count, it helps to scale for the number of characters.


Castle of the Damned

2♠ Zombies! Cx2 
3♠ Bat Swarms xC – Disadvantage to surprise them.
4♠ Giant Rats Cd4 –  On Death 35% chance to reveals as a Wererat at full HP same initiative – Disadvantage to surprise them.
5♠ Fade to Gray – Wraiths xC + Specters D6
6♠ Skeleton Cavalry – A Large Room with 2C Skeletons Mounted on Skeletal horses. If a Mounted Skeleton moves 20′ in a straight line before attack they have advantage and automatically critically hit.
7♠ Ghouls 2C + Giant Bats xC – Disadvantage to Surprise them.
8♠ Toxic Zombie Hoard -Cd6 Zombies, if they pass Undead Fortitude all adjacent creatures take d6 poison damage.
9♠ Court of the Damned – D4+C Vampire Spawn – Spawn roll D20+6 vs Characters passive perception to surprise the party.
10♠ Skeleton Defenders Cd3 Skeletons with heavy armor, shields (+4 AC) and spears.
J♠ The General – Wight Lord (125hp [physical dmg resistance], AC 16 Wight with Lance) mounted on Hydra with C heads, and C Zombies
Q♠ Banshee – The doors magically lock behind you until the Banshee is defeated. Knock or other powerful magic is the only other out.
K♠ Devourer + Zombies xC
A♠ Vampire Lord – If you have the A♢ or destroyed the Vampire’s resting place (J♣) the vampire cannot use its Misty Escape

2♣ Pit Trap – First 2 characters in marching order may make perception check DC 20 to spot the trap, dwarves have advantage. If they fail, in marching order each character makes a DC20 Dex save to avoid each following character gets a +2 (its easier if you were at the back). Falling is 2d6 bludgeoning + d12 piercing on a failed save. If all characters fall the party gets a DC 15 Group Athletics check or they die in the pit.
3♣ Hypnotic Mirror – DC13 Wisdom Save or turn against the party till unconscious (players who turn against the party are on the same team).
4♣ Dead Bodies – Wisdom save DC10 or disadvantage on next initiative
5♣ Necrotic Ward – A character proficient in Arcana or through the use of a spell may read the magic runes and know them for what they are, otherwise all characters immediately make a DC14 Dexterity save or take 8d6 Necrotic damage, half as much on a successful save. 
6♣ Haunted Chapel. 3 ghosts emerge as the party enters. May be be dismissed with DC20 Religion check (1 Chance)
7♣ A Kenku Assassin fires a poison bolt at the character at the back of the marching order unless a character has a passive perception of 30+. A Neutral or Evil character may attempt a DC13 Persuasion check to gain it as a follower.
8♣ What is Lost – A room collapses, DC10 Dex save to retreat or take 2d12 damage. Draw cards until you draw a red card, discard it. Place the rest on top in random order.
9♣ Flooded Grave – A snake filled pool of water stretching 60 feet leads to any exits this room has. Characters wearing medium or heavy armor must make disadvantaged athletics checks for each turn in the water or they cannot move further that turn, additionally those in heavy armor suffer d12 damage unless they have water breathing. Each character that ends its turn in the water is pursued by 2 snakes and each makes a +0 attacks each causing d12 poison damage. A character may attack snakes with disadvantage any damage slays, and you will not be further pursued unless you re-enter the water. You may help adjacent allies attack their snakes.
10♣ A Portcullis Slams down behind you. 50 Cumulative Strength to Break or discard a Rest Card to disable. You cannot back track until you defeat this challenge and you are trapped if no further rooms are generated.
J♣ Vampires Resting Place – If you have drawn the A♠ at any point in this game you may destroy the Vampires resting place after facing a Helmed Horror, otherwise a character must pass a DC18 Intelligence Check to do so, if you do no destroy the resting place shuffle it back into the deck. The Helmed Horror has a 60% chance to be immune to specific spells cast on it of level 2 or higher, max 3.
Q♣ Entropy – Draw a card, if its red make a DC 15 Group Intelligence Save to play it, otherwise discard it.
K♣ Impending Doom – Draw cards until you have 2 black, stack them, you must face each of them in order before proceeding. Place any red cards drawn on the bottom of the deck.
A♣ Cohort of Evil – Combine next two Encounters (Stack 2 cards as one room) draw cards till you get 2♣s. Place the rest on top of the deck in random order.

J Milestone Level Up (Optional)

2♡ Short Rest
3♡ Short Rest
4♡ Short Rest +Inspiration
5♡ Short Rest DC12 Con Check to Save
6♡ Short Rest DC12 Int Check to Save
7♡ Short Rest DC12 Nature Check to Save
8♡ Short Rest Save
9♡ Short Rest Save
10♡ Short Rest Save
J♡ Long Rest
Q♡ Long Rest +Inspiration
K♡ Long Rest DC 15 Survival Check to Save
A♡ Long Rest Save

2♢ Treasure Chest d100 gold per character + Inspiration
3♢ A Strange Invitation – +1 Weapon of Random Type d20 1 dagger, 2 Longbow, 3 Javelin, 4 Light Hammer, 5, Mace, 6 Staff, 7 Sickle, 8 Spear, 9 Lt Crossbow, 10 Whip, 11 Flail, 12 Glaive, 13 Greatsword, 14 Halberd, 15 Maul, 16 Morningstar, 17 Pike, 18 Trident, 19 War Pick, 20 Warhammer 
4♢ Greater Healing Potions d4+1.
5♢ Runic Scrolls – Characters who identify these items, either by standard means  or with a short rest may identify them as protection runes which may be permanently to armor. The first grants resistance to Necrotic Damage. They other a random damage type as follows: d12, 1=Slashing, 2=Piercing, 3=Bludgeoning, 4=Cold, 5=Acid, 6=Psychic, 7=Fire, 8=Necrotic, 9=Radiant, 10=Force, 11=Thunder, 12=Lightening.
6♢ Alchemists Lab – d6+1 rolls on Magic Item Table B (-11, min 1)
7♢ Wizards Room – d6 spell Rolls on Magic Item Table C (-11, min 1) +1 level 4 scroll.
8♢ Bag of Fangs –  Contains 1D4+C carved wooden Dire Wolf canines. When buried, a fang quickly sprouts a wolf-like tree golem with d4 x user-level HP, AC 14, and uses the users proficiency bonus for attack and damage bonuses, a successful strike does 2d4. They are vulnerable to fire damage and immune to poison. 
9♢ Wondrous Stash – 2 Rolls on Treasure Table D (-5, min 1). +Inspiration
10♢ Cowering Tentacles – Make a group Arcane check DC10 (half must pass). On success a Flumph approaches the party. Good aligned characters may make a DC12 Persuasion roll  to gain the Flumph as a companion (highest roll has preference).
J♢ Lost Expedition – A figure stands over 3 dead bodies, they are startled when you enter but relieved to see you once they realize you might be their salvation. Any character wishing to take on a companion make a charisma check, the highest roll takes them. Roll a d4, this person is a: 1 Gnome Scout, 2 Human Priest, 3 Dwarf Veteran, 4 Elf Knight (all in the MM appendix); the other 3 are lying dead on the floor.
Q♢ Brand of Flames – A club wrapped in spiked chains (1D6 Bludgeoning + 1D10 fire dmg). If identified a wield may attune to it, then the character can infuse a their attack with Fire Bolt (dmg based on their lvl: 1st level (1d10), when you reach 5th Level (2d10), 11th level (3d10), and 17th level (4d10)) 5 times a day. The wielder also takes 1d4 fire dmg backlash when they use its power. When you attune make a DC 15 Wisdom save or suffer 2d6 Fire damage. Once attuned you may transfer the chains to a different weapon which removes the enchantment from the club (once per day).
K♢ Treasure Hoard – 1 roll on Magic Item Table H, 2 on G, 3 on F. d10x1000gp of items per player. +Inspiration
A♢ Hero’s Calling – One Item from treasure table I. Players have right of refusal in descending Charisma score order. +Inspiration

J Milestone Level Up (Optional)

What’s left? To complete this deck I’d like to add room descriptions for more of the encounters, and obviously lots of playtesting along with tightening up the rules.

Extra Rules

All characters may start with inspiration.

Unless otherwise stated NPCs make or fail saves the as their leader outside of combat.

Options

Secret Doors If a room must connect to another room this means the door you just found is a secret entrance. If you can enter an unexplored room through a secret entrance you gain advantage on the surprise check. You may mark these with a token such as a penny.

Treasure Face cards which are combat encounters generate treasure hoards when they are completed. Number cards generate regular treasure.

Alert Level If you flee from combat with intelligent creatures 4+ there’s a 50% chance the entire dungeon will go on alert. This grand disadvantage to all surprise checks.

Companion Limit A character may have companions of the same alignment equal to 1+Charisma Bonus.

Exit When you draw the last card of the deck if it is a room with more than 1 door it is a dungeon exit.

Fleeing to flee from a combat encounter discard a red card then shuffle the current encounter back into the deck. Keep in the mind the secondary consequences of shuffling.

Difficulty Setting to reduce the difficulty especially if you choose to not shuffle harder encounters to the bottom of the deck you may start with a number of rest tokens which function just like the cards.

Like the article? Check out the podcast where we discuss the original concept!

Thanks for reading! I’ll make some more decks soon. Let me know if you’re interested in a printed copy.

-Jacob