Friday, July 16, 2010

Simple Multi-Ability Checks in Classic D&D

Over at The Eiglophian Press G. Benedicto made a nice post on ability checks in Classic D&D. It turns out that we both use the same general method - rolling handfuls of 6-siders, where a success occurs if one rolls the target ability score or under. For lack of a better name, the algebratron in me has always called this the “xd6” method, while Mr. Benedicto calls it “ESDVAN” for:

Easy: 2d6
Standard: 3d6
Difficult: 4d6
Very Difficult: 5d6
Arduous: 6d6
Nigh-Impossible: 7d6

For instance, if a character wants to break down an average door I’ll have her throw 3d6 to see if she can roll her Strength or under. Really heavy door? 4d6. Iron-braced door? 5d6. Works great! I particularly like this method because of its scalability and bell-curved probabilities. It’s much more useful than rolling a d20, which is another common method for D&D ability checks.

In most situations it’s pretty obvious which ability score is appropriate for the problem at hand, although sometimes I wish I could combine two abilities for a check. For instance a few sessions ago someone wanted to do a complex long jump / oil flask toss move. I had them check against Dexterity, which was fine, but I was kind of wishing I could include a Strength component as well. After thinking about it a bit yesterday, this simple solution came to mind: Roll against the sum of the two abilities using d12s:

Easy: 2d12
Standard: 3d12
Difficult: 4d12
Very Difficult: 5d12
Arduous: 6d12
Nigh-Impossible: 7d12

The maximum possible value for the sum of two ability scores is 36, which is also the maximum possible roll for 3d12. Anyway, I need a use for all those dodecahedrons in my dice horde…


  1. You could always make the check against the average of two scores instead of the sum...

    It would leave your shiny d12s sleeping in your dice horde of course... but just a thought.

  2. @silentboba - Yes, that's also a fine idea. That was actually the first thought that crossed my mind, but I figured at the table it would be faster to simply sum vs. summing then dividing (then rounding in cases where you get an odd sum). On the other hand, summing 4 or 5 d12s could take a few seconds as well. Maybe I'll try both and see which goes most smoothly.

  3. Yeah, this is gold and will definitely see implementation at my table.

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  5. I was wondering about what to use for OD&D instead of my ususal "stat or less on D20."

  6. Algebratron = a psionic robot who uses complex equations to tear his victims minds apart!

  7. Added as well to Links to Wisdom

    Not sure it's the right place for this house rule but hey ho