Monday, August 6, 2012

"Exploding" D&D Wilderness Encounter Checks

In OD&D and B/XD&D you check once per day to see if there's a random wilderness encounters (Cook/Marsh Expert has allowances for multiple checks per day, buts it's kind of vague).

That's fine but what about in adventure stories where the encounters don't stop? One dude gets eaten by a giant snake, another gets a poison dart in his neck and a third drowns in quicksand. Before noon no less.

To account for this I've worked out an "exploding die" derived wilderness encounter check that uses the sum of an infinite series calculations to maintain roughly the same odds as the original check.

The idea is every day you roll a wilderness encounter check; if there is one, roll another wilderness encounter check and than roll again and so forth (don't worry, probabilities ensure that there won't be 154 encounters). This determines the total number of random wilderness encounters the party encounters over the course of that day.

Clear, Grasslands, Inhabited, City: Was a 6 on a d6, now 1-2 on a d12 or 14%.

Woods, River, Desert, Hills, Barren, Ocean, Aerial: was a 5-6 on a d6, now a 1-3 on a d12 or 25%.

Swamp, Mountains, Jungle: was a 4-6 on a d6, now a 1-4 on a d12 or 33%.


  1. So, the other dude who gets the poison dart - does this mean you've got a Wandering Traps table too? That would be fairly awesome

  2. Well, in principle I would use "wandering traps" (such as hazards like quicksand or tiger pits), but the poison dart was actually from a cannibalistic jungle hobbit.

  3. In roll three times a day and three times a night (1 in d6). I can't remember doing it otherwise. Thing is, I can't remember where I picked that up, either. AD&D?
    Just checked, as the DMG is on the table... This encounter frequency is reserved forests and swamps, but with a 1 in d10 to d20 (from wilderness to civilised areas). Of course, I use much lower encounter numbers and have always non-combat encouters* on the tables... pilgrims, traders and such things.
    Hm, I have to think about that...
    * (Well, most of the time they are non-combat encounters, but with PCs you never know...)

  4. Dungeon of Signs just had cannibal hobbits as well...

    Maybe "cannibal" should just be assumed for hobbit encounters

    1. Dark Sun had them as well. For some reason I always consider that to be the case. They are perfectly decent fellows when they get 6 meals a day and all the pipeweed they can smoke, but they all are just 3 meals from eating the next traveler who comes along.

  5. I think there might be an error in the first item on your list.

    For "Woods, River, Desert, Hills, Barren, Ocean, Aerial" and "Swamp, Mountains, Jungle", you've made encounters less likely: 1 in 3 -> 1 in 4 and 1 in 2 to 1 in 3 respectively.

    But "Clear, Grasslands, Inhabited, City" is 1 in 6 for both values.

    Perhaps it should be 3 in 20 (which is close to 1 in 7).

  6. rorschachhamster the 3 times thing was a AD&D 1 or 2e thing. but, I remember doing it three times a day. Once every 8 hours as that is the time one would spend traveling without pushing through.