GM: You walk through the door. You see a 10' wide by 8' tall corridor that continues well past your torch light.
Player A: I search for traps. (rolls) 16.
GM: You don't find any.
Player A: I search for secret doors. (rolls) 5.
GM: You don't...
Player B: I search for secret doors. (rolls) 20!!
GM: You don't find any.
Player C: We walk 10' down the corridor.
Player A: I search for traps. (rolls) 13?
The fun of exploration and the complex narratives woven into many dungeon delves are frequently disrupted by routine, repetitive rolls to search for things that usually aren't there. While some groups enjoy the rhythm of applying the mechanics this way and the assurance that the GM didn't miss an opportunity for them to search, other groups struggle with maintaining their momentum through a dungeon. These suggestions are meant to encourage more streamlined play when exploring.
Unless your adventurers find themselves in The Chaotic Murder Dungeon of Loon the Mad™, the placement of traps and secret doors should make sense. Secret doors should aid the antagonists in moving between areas that are important to them. Traps should be located in places that make sense for the inhabitants of the edifice. These are things that players and characters should be able to reason over. For secrets and traps that particularly important to the adventure, the party should have the opportunity to get clues from NPCs or other sources earlier in the adventure. Think of any good heist caper. Much of the buildup is in the protagonists gathering information on the target and preparing for their run at it. If characters are operating in this mode, it makes that one special surprise--Loon the Mad just installed a mimic in the vault--all the more exciting.
The "System Reference Document 5.0" already includes the hint that the GM can use passive checks "for a task done repeatedly, such as searching for secret doors over and over again". (SRD, 78) GMs should take this advice more often. The players should describe their usual pace and routine for the setting, along with their marching order, and the GM should roll for any stretch of hallway or room the party enters. This requires a bit more tracking on the part of the GM, but can make games much smoother. The GM needs to keep track of the relevant passive versions of the stats for the party, not just perception. Simply add the modifier to 10 for each stat or skill that is likely to come into play and that is the passive version. This little bit of extra effort pays off though, particularly when you can make plenty of passive checks without players knowing what you are checking for.
One challenge with this approach is that many traps and secret doors are described with the DC to find them, implying active checks. It's easy to turn these DCs into modifiers to use against the passive version of the PC's abilities. The modifier to use for the passive check is the DC -12.
Here's an example to show why that works. If a secret door is DC 15 to find and the party's rogue is +6 to find it, they would need a 9 or higher to succeed. Turning that around, the rogue's passive stat is 16. If the rogue would usually succeed 12 times out of 20, the door should stay hidden 8 times out of 20. A roll of 13 or higher means the door stays hidden in a passive check. The DC of 15 minus 12 gives a modifier of +3. 13 + 3 = 16.
If players are working together in an activity--two skilled rogues are searching for traps--the passive checks are made at disadvantage for the environment. Always roll 2D20 of different colors when making passive checks. Use one as the actual die when there is no advantage or disadvantage.
When the characters have strong reason to believe that a trap is present or they need to find a suspected secret escape route and the stakes are clear, the players should make the rolls.
Puzzles feature prominently in many dungeons. What do you do when the wizard is unconscious and the other min-maxing players at your table with characters with intelligence stats 6 or more points lower than their real intelligence start to solve the symbolic logic puzzle? What do you do when the 19 Intelligence member of your party can't get the simple tic-tac-toe-based puzzle you slapped together on the bus on the way to the session?
The second situation is easier than the first. Players can make Intelligence or Intelligence(Arcana) or Intelligence(Investigation) checks for hints that get better based on how well they do. For really high rolls, the GM can simply describe how the party solves the puzzle and move on.
The first situation is harder. Many players like puzzles, but what if they decide to roleplay characters who are not as smart as they are or who are just plain dumb. Like Harrison Bergeron, those players should be encumbered in some way. Here are three quick mechanics that you can use for this situation.
- Roll for It: The player passes a note to the GM with a few words making it clear what they would like to say. The GM assigns a DC for that idea, using raw Intelligence or a suitable skill. The player must make the appropriate check before their character can share the idea. Failure means the character does not have access to the player's idea. We're essentially treating thinking like any other ability or skill.
- Inspiration: The player can spend an inspiration to role play beginner's luck or a "so dumb it's smart" approach to solving the puzzle. The player and character solve the puzzle, just not in the same ways. The player gets the fun of puzzling. The character lucks into it. This option has the most potential for entertainment.
- Raise the Difficulty: Adjust the difficulty of the puzzle based on the collective intelligence of the party. Calculate the average intelligence of the party and round down. For each point below 12, or 15 if you want to make things more challenging, adjust the difficulty of the puzzle in some way. Remove hints. Cut the amount of time available to solve it. Add a complication, like a missing piece. The players are still solving the puzzle, but their character choices have consequences in game play.
If player-solved puzzles are important to your play group, you can make more radical adjustments to the game. Replace the Intelligence stat with a Knowledge stat. It's purely about what characters know, not natural intellect.