what if fabula stats but pbta/wodu results?

2024-05-12‍

Relating to my post about statistics for Fabula Ultima roll results, as well as my looking at making a World of Dungeons (WoDu) hack, I started to think - what if, instead of using the standard WoDu (and in fact general PBTA) rule of "roll 2d6 and add a modifier", you used Fabula Ultima-style stat dice?

The basic result table 🔗

If you're reading this post you probably know this, but the basic resolution system in PBTA games, and World of Dungeons which is a lightweight PBTA type thing, is roll 2d6, add a modifier maybe, and consult this table ("meaning" is taken from WoDu):

Roll	Result	Meaning
2-6	Failure	things don't go well and the risk turns out badly
7-9	Partial success	you do it, but there's some cost, compromise, retribution, harm, etc.
10+	Full success	you do it without complications

WoDu actually adds an extra level on a 12+, "critical success" - "you do it perfectly to some extra benefit or advantage". But I'm not going to use that at this point.

If you've not checked out World of Dungeons I advise you to - it's free, it's six pages (two of which are character sheets) and it's the basis of lots of cool hacks like Remix and FIST.

Standard WoDu 2d6 🔗

So first let's look at the usual numbers. In WoDu as it is, stats range mostly from 0 to 3, and you add your stat to a roll, maybe with some extra modifier or penalty, though as standard there aren't any in the rules, so really only the 0 to 3 rows here are relevant.

All numbers in these tables are percentages btw, and may not add up to 100 due to rounding.

Modifier	Fail	Partial	Success
-3¹	83.3	16.7	0
-2	72.2	25	2.8
-1	58.3	33.3	8.3
0	41.7	41.7	16.7
1	27.8	44.4	27.8
2	16.7	41.7	41.7
3	8.3	33.3	58.3
4	2.8	25	72.2
5¹	0	16.7	83.3

Anydice program generating these numbers²

What's pretty clear here is that your failure chance goes down dramatically with skill, but your chance of full-on success doesn't go up a lot. Even with a +3 your chance of a partial is 1/3 and you make a full success only 58% of the time.

Fabula-style dice chain stats, dual rolls 🔗

Fabula Ultima takes a different approach to stats. In Fabula, you have stats on a dice chain - d6 > d8 > d10 > d12 - and every time you make a resolution roll, you roll
two of them (possibly the same one) and add them together. I like this because it gives a sense that tasks can involve more than one ability, and stops one being dominant. For instance, attacking with a weapon that depends mostly on how strong you are like a waraxe is a MIG+MIG (Might) roll; one that also involves agility like a spear is a DEX+MIG roll; a pistol uses a DEX+INS (Insight) roll. In Fabula, the sum of these rolls is compared to a target, usually 10 - it has no "partial success" rules - and also there's a complicated system for critical success and failure which I'm not going to go into here.

So what if you use those rolls but with the PBTA/WoDu results table? After all, the starting value of a stat in Fabula is d6, so a basic roll is going to be 2d6, just like in WoDu. In addition the highest stat you can get is d12, and a 2d12 roll has an average result 3 points higher than a 2d6 one, coincidentally the maximum stat value in WoDu.

Well, this is what happens. I included d4 as a possible stat because why not allow for a weaker-than-average stat?

Roll	Fail	Partial	Success
d4+d4	81.3	18.8
d4+d6	58.3	37.5	4.2
d4+d8	43.8	37.5	18.8
d4+d10	35	30	35
d4+d12	29.2	25	45.8
d6+d6	41.7	41.7	16.7
d6+d8	31.3	37.5	31.3
d6+d10	25	30	45
d6+d12	20.8	25	54.2
d8+d8	23.4	32.8	43.8
d8+d10	18.8	26.3	55
d8+d12	15.6	21.9	62.5
d10+d10	15	21	64
d10+d12	12.5	17.5	70
d12+d12	10.4	14.6	75

Anydice program for the fabula style rolls³

So from this you can see a few things:

The chance of failure is slightly lower but not significantly so, e.g. 15% with d10+d10 vs 16.7% with 2d6+2
There are slight differences with one high stat and one low stat vs two equal ones. d6+d10 has a 45% success chance vs d8+d8 which is 43.8%. But that's not significant either.
What is significant is that the chance of a success goes up faster than with 2d6 rolls as you get better, and the chance of a partial goes down faster too. d12+d12 has 75% success, 14.6% partial, vs 2d6+3 having 58.3% success, 33.3% partial - over twice the chance of a partial if you use modifiers. If you really like partial successes? well I guess this is not something you'd want to do.
Because you have two stats contributing, you have more graduated levels of results, twice as many. Whether this actually means anything is arguable. But it might feel like it does, which is what counts.

Conclusion 🔗

There's no hard conclusion here, but it's something I might explore for my current project because (a) I really like the dual-stat roll system, (b) I also like the WoDu resolution table, and (c) the two apparently work well together - I personally don't like how partials still dominate with high bonuses in WoDu, I feel you should be significantly more likely to succeed in these cases.

At this level it probably isn't worth rolling - find a different question to ask or just say it happens. ↩︎ ↩︎


FAIL: 0  
PARTIAL: 1
SUCCESS: 2

function: getresult ROLL:n {
 if ROLL < 7 { result: FAIL }
 if ROLL < 10 { result: PARTIAL }
 result: SUCCESS
}

loop BONUS over {-3..5}{
 output [getresult 2d6+BONUS] named "Modifier [BONUS]"
}

↩︎


FAIL: 0
PARTIAL: 1
SUCCESS: 2

function: successtype ROLL:n {
 if ROLL < 7 { result: FAIL }
 if ROLL < 10 { result: PARTIAL }
 result: SUCCESS
}

loop DIE_FIRST over {4,6,8,10,12}{
  loop DIE_SECOND over {4,6,8,10,12}{
    if DIE_FIRST <= DIE_SECOND {
      output [successtype 1dDIE_FIRST + 1dDIE_SECOND] named "d[DIE_FIRST]+d[DIE_SECOND]"
    }
  }
}

↩︎