The Heist Clock is an idea for how to leverage the classic exploration turn cycle to run heists in D&D. Here's the basic idea.
Start with your favorite version of D&D. I like B/X as a starting point for this, but any classic version will do out of the box. With 3rd edition and newer versions, you'll have to institute your own timekeeping and wandering monster check conventions or borrow the ones from a pre-3rd edition version of D&D.
Here are a few basic assumptions I started with:
- 1 turn equals about 10 minutes.
- Many actions cost 1 turn worth of time, including movement at cautious exploration speed, and also things like combat, searching an area for traps, picking a lock, and so on. These items move the clock forward.
- Every 2 turns, check for wandering monsters. Monsters are encountered on a 1 in 6.
- Check surprise for each party. On 1-2, the party is surprised.
- Reaction checks: 1 attack, 2 hostile, 3-4 uncertain, 5 no attack, 6 friendly/helpful.
- Working traps are sprung on a 2 in 6 chance if passed or if an action is taken that might trigger them.
For the Heist Clock, the turn becomes somewhat more abstracted. A turn is often ten minutes, but it may be five minutes or less. The GM can still keep rough track of time, but what becomes more important is ticks of the clock.
When the heist begins, the clock starts ticking.
The following actions cause an additional tick of the clock.
- Cautious, stealthy movement (i.e., movement at the default exploration rate)
- Climbing or overcoming a physical obstacle
- Picking a lock on a door or vault
- Evaluating a lock, door, vault, or object for traps
- One attempt to disarm a trap or other device
- Any spellcasting that includes a verbal component
- Forcing a door (quick, but loud)
- Taking out a sentry, if done relatively quickly and without too much noise
- Leaving evidence that you've been in the place (the room is a mess after you searched it, there was a fight and you can't cover it up, you're scattering the bodies of sentries all over the place, etc.)
- A combat
- Checking a 10 by 10 area for traps
- Checking a small room for secret doors and hidden treasure caches
- Stopping in the middle of the job to plan, plot, argue about shares, etc.
- Anything else that might increase the likelihood of a complication arising
Every 2nd tick, a check is made for complications. Complications are roughly equivalent to Wandering Monster checks, but a bit more varied. If the place is not on alert, a complication occurs on a 1 in 6. If the place is on increased awareness because you've made a little noise, a complication occurs on a 2 in 6. If the place is on alert, a complication occurs on a 3 in 6.
If a complication occurs, roll 1d20 on the following table to see what kind of complication arises. This table is a template table, created with the rainy city in mind, but fairly adaptable. When prepping for each heist, the DM should review this table and personalize selected entries to reflect the particular location that the PCs are hitting. If it says "Magic/Weird Trap," for example, the DM should decide what that trap will be as part of prep. And so on. Here's the template:
Roll 1d20 for a Complication
- Magic or weird trap
- Locking bars/gates/doors
- Silent alarm calls in external help
- Mundane trap
- Alarm is tripped, raising alert level or calling guards
- Guest of the house
- Family member of the house
- Small guard patrol (define "small" based on the locale)
- Large guard patrol (define "large" based on the locale)
- The Lord of the house
- False cache is discovered (cache is alarmed or trapped)
- Animated object
- Genius Loci
- Ghost or poltergeist
- Cursed item (item is locked away, alarmed, or trapped)
- A curse/geas is triggered
- Magic or weird guardian
- Cross a pentagram, something is released
- Rival crew of thieves robbing the place at the same time
In addition to the above random complications, it's also possible to seed the place with random discoveries. I'm using a bunch of floorplans from mansions and large houses for most of these break ins, with some D&D style maps thrown in as well. It's easy to assign 2d4 locations in the house as sites for potential discoveries. If the players search an appropriate room and succeed in finding secret or hidden things, they find the discovery in addition to whatever else might be there. This table can be tailored to the mission as well, or these can be rolled up ahead of time.
- Trapped demon, imp, ifrit, ghul, fairy, or other magical being tied to a pentagram or item
- Magic pool, fountain, deck of cards, other source of random good and bad things for the risk takers
- Magic gate, goblin door, wardrobe
- Secret room
- Spell components or lab ingredients
- Incriminating evidence against the owner of the house, e.g. of conspiracy, cult membership, etc.
- Art objects
- Papers, deeds, letters of marque
- Magic item
- Genius Loci who will help the party, dislikes the owner of the house
- Other ally (servant, family member, guest, etc. who dislikes the owner or wants a cut)
- Memento mori of value
- Vault or hoard
- Secret escape tunnel or other passage out of the house