Non-Homogenous Random Tables

In the balanceRandom tables are a great way to introduce some unpredictability into a game, but they can also be a tad predictable , same-ish, consistent, ‘one size fits all’ … mono-dimensional?

I thought it would be nice to have a random table that responded to a situation/condition, rather than any given result having the same likelihood.

For example, I like the idea that:

(a) the deeper you are in a dungeon, the more likely the random encouters will be dangerous; or

(b) the further from town you are, the more likely you’ll encounter goblins; or

(c) a landscape than favours some creatures in one area, and other creatures in a different area, but where there is a theoretical continuum between the two areas and so encounters; or

(d) Henchman ‘moral check’ indexed to the threat level … etc.

There are several solutions to this, the simplest of course being to have different random tables for different situations, or even to use modifiers.

Another way to go, the idea that I quite like, is to stratify the encounters from one extreme to the other and use an advantage/disadvantage type mechanic to ‘tip’ the results depending on the current situation.

Below is an example lifted straight out of my procedural adventure ‘Carapace’. The random table is ‘stratified’ into three main layers: the lowest values (blue layer) giving giant ants, the middle values (green layer) giving wildcard monsters, and the highest values (yellow/pink layers) giving the boss monster and its elite guards.

So, in ‘Carapace’ the idea was that the area being explored (a giant ant’s nest) was divided into 4 Zones, with the ‘Big Bad’ most likely being found in Zone 4. The more mundane monsters being located in Zone 1 and 2. There was also a fair chance of getting ‘wild card’ monsters basically anywhere.

Carapace encouter table as per zone

If it is not clear from the above, you roll a number of D20s equal to the zone you are in (so 3 x D20 in Zone 3), and use a tailored advantage/disadvantage mechanic to influence the result (to swing the result towards one end of the table or the other).

So, for example in Zone 1 you’ll never get the Queen Ant (the boss encounter), in Zone 2 it’s 1 in 400 (i.e. possible, but improbable), in Zone 3 it’s 3 in 20 and in Zone 4 it’s 4 in 20 (i.e. now getting quite likely).

The reverse of this for example would be, in Zone 1 a lone worker ant is 1 in 20, but in Zone 4 it’s 1 in 160,000.

Even if I’ve messed the maths up above, I think the idea is clear enough, that is you can tip the result of a random table using a system like this. Of course, this idea could be applied to any random table outcome (not just encounters), e.g. types of terrain, NPC reaction dependent on closeness of alignment etc.

Again, there are other solutions, I just think this one appeals to me. I’m also fairly certain this has been done before in some form at least, but this post is an attempt to flag the idea up as an option for the old ‘DM tool kit’.

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InHotS the cover imageMe on DriveThruDriveThru; at the moment I’m mainly pimping my procedural High Seas ‘Hex Crawl’ – In the Heart of the Sea.

6 thoughts on “Non-Homogenous Random Tables

  1. Donovan Peterson

    I use something similar but instead of d20’s I use cumulative d6s. Safe zone equals d6, most dangerous zone equals 4d6. 1-3 are mundane encounters, 24 is an epic encounter. Numbers between get increasingly more dangerous as they ascend. Players can tame areas, lowering the number of dice rolled in that area.


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  4. TBeholder

    Everything from (a) to (d) can be done (and sometimes is) using a plain adjustment to the roll. Whether with 1dX flat or ndX bell distribution.
    The dice pool works, but it increases distribution width, which is not always desirable. This can be compensated by making the entries redundant, of course, but fixed-width distribution can make fine-tuning of a table easier, both because it’s immediately obvious how far linear shift goes, and because rate of adjustment step : distribution width is arbitrary and remains constant.


    1. The Rethinkler

      I was thinking I’d prefer an approach like this. You could have zones with different threat ratings in a dungeon, and the threat rating is added to the encounter roll. Or you could use a ‘how many rooms from the nearest exit’ type of rule rather than having zones. In the case of a hexcrawl, you could add the number of hexes away from the nearest town or other sanctuary you are.

      Not totally sure how this affects the probabilities, but I suppose this approach would mean lower results on the encounter table will be eliminated deeper in the dungeon/wilderness, which could be a good or bad thing depending on how you structure the table.

      For instance, I think it would be a good thing if some of the lower encounters are things like ‘1d4 orcs’ or something to that effect. Perhaps orcs only travel in larger bands deeper in the wilderness so they don’t get eaten by bigger nasties.

      Liked by 1 person


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