So you’ve decided to use playing cards instead of dice to determine random encounters in your dungeon. The next step is to create an encounter table that corresponds to your cards, so that a single draw not only tells you that there is an encounter, but it also tells you what is encountered.
Going with six cards corresponding to encounters but assuming that you don’t have an easy way to distinguish between Jokers, you’ve got 5 spots to fill. That’s not as much variety as you see on a typical dungeon encounter chart, so that’s a tradeoff — but maybe not all that much of a tradeoff.
There are all sorts of dungeon encounter tables out there using all sorts of dice, but I’m going to state with no supporting evidence whatsoever that 2d6 tables are a fairly common option. Looking at the distribution of 2d6, the five most common results (5-9) will come up 66.7% of the time, so you’d end up with one of those five results well more than half the time anyway.
At this point, it’s just a simple matter of filling out the encounters, remembering that the Joker encounter can come up twice. A simple first-level dungeon might look something like this:
- Joker — 4d4 kobolds
- Jack/Spades — 1d3 giant spiders
- Queen/Spades — 2d4 orcs
- King/Spades — 2d4 skeletons
- Ace/Spades — 3d4 goblins
Personally I’d add a little “dungeon dressing” to the mix, but I would assign that to a different suit. It increases the overall chance that something is encountered, but it doesn’t cut into the odds of running into a standard wandering monster. If the PCs keep revisiting the same dungeon level and the same dressing result keeps coming up, it’s clearly an adventure hook waiting to happen.
- Jack/Clubs — Whispering voices seem to come from the shadows
- Queen/Clubs — The low rumbling of earth shifting is heard overhead
- King/Clubs — A wailing spirit appears but ignores the PCs
- Ace/Clubs — The temperature drops suddenly, forming frost on stone and metal
You can also use this method to incorporate special hazards/effects that can potentially occur after a certain amount of time. To riff on one of my dungeon dressing effects from above, PCs exploring a mine could be risking a cave-in. You could note that for every Diamond face/ace drawn, the PCs hear rumbling and you make a mark in your notes. When the fourth Diamond comes out, a cave-in occurs around the PCs.
Finally, if you want to spice things up with an encounter that’s really tough for that dungeon level, such as an ogre in an otherwise 1st-level dungeon, it’s important to remember that encounter must always correspond to the ace of spades.