The full rules to One Deck Dungeon are available in PDF format. The current version is v1.7, updated in 2022. A complete list of changes from v1.0 to v1.5, is listed in the patch notes. Rulebook changes since v1.5 were only to make things more clear, updates to diagrams and typo fixes, etc. The most notable example is that confusion existed over what happens to dice at the end of a turn.
At the end of every turn, all dice are returned to the general supply, unless exiled or stored on a hero card.
Many of the FAQ entries below are from v1.0 rules questions.
Invisibility Potion
The Invisibility Potion should read "Spend two time before an encounter. Skip to the Claim Loot phase."
In a 4P game, an Invisibility potion skips one of the two encounters. Effects like Flames, Frost or Drain do not occur.
This change does not significantly affect the balance of the Invisibility Potion, it still costs two time and the potion cube to skip an encounter and claim loot. Now its interactions with other skills and rules much clearer, as it no longer requires you to 'flee'.
Stairs Card
The Stairs Card should include the phrase "If you reveal the Stairs Card while spending time to start a turn, you may choose to descend immediately."
This prevents some issues related to open doors and forced Explore turns with an empty deck.
Components List
Your game should include 6 white potion cubes, not 8 as stated incorrectly in the rulebook.
Challenge Tiers
The updated rulebook includes a new section on page 23 called Challenge Tiers. These allow you to reduce the difficulty of One Deck Dungeon. Expert Mode is the rules as originally written. Standard gives you one free card as XP to start each game, and Novice lets you start each game at experience level 2. In addition, Expert gives you two extra campaign checkmarks per game, and Standard gives you one.
Q: How does the Dragon's Cave work for spending time at the start of the game?
A: The Hall of Statues makes you spend five time before starting each floor. You'll spend five time for that, two time for your first turn exploring, and then two more for your second turn entering a room. Before your first encounter, you will have spent nine total time.
Q: What happens if the Stairs Card is revealed while spending time to start a turn?
A: If there were not enough cards in the deck to spend all the necessary time, damage tokens are placed on the Stairs. The errata to the Stairs Card above states that you can choose to descend immediately. If you don't, you'll have to enter a room. You cannot explore if there are no cards in the deck.
Q: Can I enter an already-open door and then flee from it?
A: No. You can only flee if you open a closed door.
Q: What happens if the Stairs Card is revealed while exploring?
A: You place as many closed doors as you can, and then the turn is over. In a 4P game, if you would place a door with just one card, discard it instead.
Q: How does timing work for "before the encounter" things: Flames, Frost, Drain, and Heroic Skills?
A: These only occur if you choose to have the encounter. If you flee, all are ignored. Flames and Frost happen before you claim dice or use Heroic Skills. These dice are just like any other dice rolled during the encounter, and can be affected by combat foe and dungeon abilities.
Q: Can Drain cause me to level up before an encounter?
A: No. You only level up during the Claim Loot part of a turn, after an encounter is completed.
Q: How does damage/time loss due to monster or dungeon abilities work?
A: You can take damage before an encounter starts from Flames, Daring Strike, or the Stairs Card due to time spent by Heroic Skills, Fade or Frost. These are not part of the consequences of the encounter, and cannot be mitigated by skills that prevent damage, nor do they count for dungeon abilities like Freezing Winds or Blade Storm.
Q: Are dice limited?
A: Yes. If you have enough attribute icons to roll more than the 8 dice available for a color, the excess are lost.
Q: How do dice limits work in a 4P game?
A: In an encounter, you and your chosen partner should have access to 30 dice: 8 of each of the 3 attribute colors, and 6 heroic dice. You may already have heroic dice on your Hero Card before the encounter starts. These black dice count against the limit of 6. So, if you and your partner both had one black die stored before an encounter, you would have access to 8 / 8 / 8 / 4 dice in the encounter, aside from those two.
Keywords: Add, Roll, Increase
"Add" means to add a die of the specified value to your pool of already-rolled dice. "Roll" means to take a die from the general supply, roll it, and add it to your pool. "Increase" means to take a die from your pool, and change what number is showing on it.
Q: What are Basic Skills?
A: Basic Skill Cards are unlocked through Campaign Mode.
Q: In a 2P game, how does sharing dice work? Can I use my partner's dice for skills? What about skills like Cleave?
A: Dice that you roll or add for any reason are "yours". This includes your attribute dice, dice rolled from your heroic skills before an encounter, dice rolled or added by normal skills, and heroic dice added by the Experience Level card (players choose who gets to roll these dice). Keep your dice separate from your partner's. You cannot use your partner's dice to pay for skills. Skills like Cleave that affect "your" dice cannot affect your partner's. You and your partner can each contribute a die together to create a heroic die. In this case, choose which player adds the new die.
Q: Can I use skills to reroll dice to avoid Split, Ethereal, Weakness Curse, or the penalty for Daring Gamble?
A: No. These effects happen immediately after rolling dice.
Q: Can I use heroic dice to pay for skills?
A: Yes. Heroic dice can be used as if they were any color, both for placing in challenge boxes, and for paying for skills.
Q: Can I use dice I gain from one skill to pay for another?
A: Yes. Once added or rolled, your new dice can be used for any purpose.
Q: What can I do if I run out of available dice?
A: You may discard dice at any time to the supply if you don't want them. This can allow you or your partner to gain them from another skill or potion.
Q: Can I use free skills more than once?
A: Each skill may only be used once per encounter, even if you can pay for it more than once.
Q: Can I use one blue die to pay for more than one spell?
A: No. Each spell is paid for individually, and dice used are discarded. You cannot carry over mana.
Q: How do I get potions?
A: You get one potion to start the game. You gain one potion each time you level up. If you identify a potion as loot, adding it under the Turn Reference Card, you add one potion cube. The "Prepared" talent gives you one extra potion to start the game.
Q: When can I use potions?
Invisibility (see the errata above) is used before an encounter. Healing potions are used at the start of a turn to heal 3 damage from a single hero, or during battle to heal 2 damage from a single hero. All other potion types are used during an encounter, at the same time you can use skills -- after rolling dice.
Q: When do I use damage and time prevention skills?
A: Use them during the encounter. During the Suffer Consequences part of the encounter, subtract the prevented damage or time from the visible icons, before taking damage and spending time.
Q: How do Freezing Winds and Blade Storm work with prevention skills / sharing damage? What time and damage count toward these triggers?
A: Freezing Winds and Blade Storm only care about damage dealt and time spent during Suffer Consequences. Ignore the costs of skills, peril choices, or combat effects. First, count up how much damage and time is on all uncovered boxes. Then, apply prevention skills that were used. If there is enough time to trigger Freezing Winds, or damage to trigger Blade Storm, add one damage. Finally, divide the damage up between characters, and then spend any required time.
If playing as the 1P Paladin, her Armor skill does not trigger until after adding the extra damage for Blade Storm / Freezing Winds.
Q: What happens if the Stairs Card is visible and causes damage during Suffer Consequences?
A: Resolve this damage after the Suffer Consequences step.
Q: On a Peril Encounter, when do I spend time for the choice I made?
A: Immediately upon making the choice, before heroic skills or rolling dice. This time is spent separately from Consequences, and so does not count toward Freezing Winds.
Dodge (Bandit)
During the encounter, you can combine any three dice (all from one hero, or 2 from one and 1 from the other) to make a heroic die, equal to the lowest of the three.
Drain (Wraith)
If you have no items, nothing happens. If Drain pushes you over the threshold for a new level, you do not level up until after the encounter. If Drain removes an item, and you have no health, the game is over unless you spend a Healing Potion immediately. In a 2P game, Drain only affects one hero.
Ethereal (Phantom)
Dice are discared before any skills can be used. If a 1 is rolled by the Rogue's Daring Gamble, the Rogue takes damage, loses time, and then the 1 is discarded.
Fade (Shadow)
Potions do not cost any time due to fade, nor do Heroic Skills(they happen 'before the encounter'). Free skills do cost one time. This time is spent immediately, not during consequences.
Flames (Fire Elemental)
This damage cannot be prevented by Dodge or Kiting. It happens before Heroic skills, so a Warrior could take the damage in order to gain and then use a heroic die with Frenzy. This damage is taken immediately, not during consequences.
Frost (Ice Elemental)
This time cannot be prevented by Fearless Charge or Poison. It happens before Heroic skills, so a Warrior could damage from the Stairs in order to gain and then use a heroic die with Frenzy. This time is spent immediately, not during consequences.
Split (Glooping Ooze)
All dice rolled can cause time loss due to Split, including rerolled dice. This time is spent immediately, not during consequences.
Survivor (Beetle)
Armor boxes on the right side of the Dungeon Card count toward Survivor.
Swarm (Goblin / Plague Rat)
The card counts itself as one open door. In a 4P game, each face-up pair of cards counts as one combined open door.
Undying (Skeleton)
Boxes on the right side of the Dungeon card count toward Undying. This time is spent immediately at the end of the encounter, but is not part of consequences.
Got a question that hasn't been answered yet?
The second half of the rulebook, the reference section, explains things in greater detail. The One Deck Dungeon forums on BoardGameGeek are also a great place to ask questions. If you want to contact us directly, you can. AsmadiGames (at) gmail. We'll continue to update this FAQ as questions come in.