PbtA with Dice Pool?

I’ve been working away on my ol’ PbtA game for awhile now (getting really close to playtest ready, which is exciting!) and as I tinker with it, I keep thinking back to this thread:

They eventually get onto the topic of “Blades-ifying” PbtA, meaning rolling a dice pool and modifiers being +/-1d instead of +1’s or advantage. I’m reeeally bad with math and have no intuitive understanding of probability, so I don’t know how this compares to your classic 2d6+x, as far as that subtle behind the scenes mathiness that affects how heroic or grungy the success rate ends up being, but I keep coming back to this idea. I’ve been feeling like my game has a few too many moving parts and places I want to give bonuses or debuffs, to the point where giving +/-1’s or dis/advantage on rolls gets to be cumbersome, and I’m wondering if I could do a really simplified version of Blades’ system that still looks mostly like classic PbtA?

Super tentatively:

  • Stats are your base pool. Let’s say you start with 0, 0, 1, 1, 2. As in Blades, roll 2, take the lowest if you’re rolling 0.
  • Something like stress, stamina, mana, etc. Spend 2 to give yourself +1d, spend 1 to give someone else +1d, pass out if you run out.
  • Gain ability tags that give you +1d if relevant to your action (rolling a generic “Act Under Fire” type thing to stop a rolling boulder, take +1d from your [Strength] tag, for example. Fight a tree monster, +1d from your [Fire] magic, etc. Kind of a mix in my head of fictional positioning from Ability tags in Masks and how this works in Lady Blackbird)
  • An extra resource like Gambits in S&V that anyone can spend to give themselves +1d.
  • Playbook moves might give +1d if you fulfill some requirement, spend a resource, get and spend hold, etc. Your classic PbtA resource repertoire.
  • Moves are still specific, not the generic Blades roll. Effectively you’re rolling and looking for your highest result. Think of any PbtA game move, just replace 10+ with a 6, 7-9 with 4-5, 6- with 1-3 (or 10+ = 5-6, 7-9 = 3-4, 6- = 1-2…? Again, so bad at probability…)

So if you really went all out with EVERY source of bonus, you could roll like, 8d…? But that’s more or less true in Blades, I believe?

What do people think of a PbtA game operating like this instead of the classic 2d6 and modifiers around that? I can’t think of any glaring reasons why this wouldn’t work, but again, I cannot stress enough how bad I am at math, so I might be missing some glaring shortcoming…

TLDR; can you replace the PbtA 2d6 roll with Blades-style dice pool without changing much else?


Tides of Gold is a FitD game (https://www.drivethrurpg.com/m/product/267572) that uses PbtA dice mechanics. It might give you an insight into going the other way.


Semi-relevant nitpick: I don’t think it’s possible to get above maybe 6d in Blades.
That said, I don’t think this solves any problems exactly either – rolling 4 or more dice in Blades feels a LOT like rolling at +3 in PbtA. Which is to say, your chances of actually failing are vanishingly small.

In fact, since I can do basic Anydice, I can tell you that 2d6+3 scores a 6- 6.34% of the time, while you will get no 4+'s on 4d6 about 6.25% of the time. That’s mighty similar, though your chance of clean success is a bit higher in PbtA on 2d6+3 – you’ll get a 10+ 58% of the time, vs only a 45ish% chance of a 6 on 4d6.

So basically: You can do this if you want, but it doesn’t solve the problem of “the chance of bonuses making failure vanishingly unlikely happens pretty fast”. So if you want to do this, do this. But don’t do it because you think it really substantially changes the math. Though technically the Blades method does eliminate the “I literally cannot fail once I hit +5” effect, but rolling 5d6 and not getting at least one 4+ is a 3.13% which, while not zero, is pretty dang low.


Calling @BrianAshford , who did this math on these very forums a few months back.

Basically: You can do it! It works. Just barely, and with a couple of kludges. But this is a thing.


@Frasersimons Never Knows Best (currently on Kickstarter) is a PbtA game that uses dice pools.


In S&V you can have 3 in a stat, +1 for push/devil’s bargain, +1 for someone assisting, +1 for a gambit, +1 from a special ability, for 7d. I have added one extra source for 8 in my pitch, it looks like. Though as you say, once you’ve hit 5, it seems like it’s a fairly moot point?

I hear you about the math, though I do think this system tips it over a little bit for me because you can still possibly get a fail no matter how many dice you roll in Blades, whereas you literally will not fail if you get a +5 mod on a 2d6. I enjoy the slightly more loose nature of being able to pull in +1d from here and +1d from here in Blades, whereas stacking +1’s or even “double advantage” seems more immediately, observably broken in PbtA, and I kept chafing at needing to implement a rule like “don’t roll more than +4” or “you can only have one source of advantage.”

Trying to do this with 2d6 and have moves that grant you boosts, an assist feature, a resource you can spend to boost yourself, etc. seemed to hit those hard barriers pretty fast, whereas here the barriers are a little harder to see, even if the probability is still pretty much rocketing behind the scenes.

Of course, another solution would be to cut back on those extra sources of bonuses I was trying to wrangle all together on the basic 2d6 version, or suck it up and implement those rules about capping how many you can have at a time.

Ah, “core” Blades in the Dark doesn’t have Gambits, hence my 6d. Though it goes to 4 in an action rating, but I don’t remember there being many special abilities that add dice. Aaaanyway…

If the “you could still theoretically fail” thing is important to you, go for it, but I think in practice, I would find it more irritating than anything else to fail by the time I had stacked 6 dice. As I said previously – it’s not really that much less “observably broken”. At the table, it’s going to feel largely the same, except that maybe once in every 30-odd rolls at those odds, you’ll get a chance to have someone annoyed by their failure. :wink:

I feel your pain though – I too have a PbtA game in the works where I am staring at it and going “Y’know, these helping rules are really strong, I guess I’m going to have to cap bonuses at +4” and not feeling great about that. I should probably crack open my preview version of Flying Circus, which is basically “PbtA but with 2d10” which would allow for greater granularity and allow you to stack more +1’s without breaking things.

All THAT said, I feel like “Don’t have a million modifiers” is, if not a core principle, certainly something that is generally accepted in PbtA games – cynical people would say “That’s because they picked 2d6”, but I think the more realistic read is “The Baker’s picked 2d6 because they didn’t WANT to add too many bonuses.” So if you want to make a PbtA game that DOES have lots of different ways of getting bonuses, you should probably reconsider using 2d6. Whether that means going to a Blades style dice pool (Not really a strong improvement, probability-wise) or to 2d10 or whatever is up to you! :slight_smile:


I’m glad to see this bubble up again, I enjoyed figuring out those dice pools. I tried to present all of the maths as I worked through the various options, if there’s anything which isn’t clear that you would like to understand, just ask.

Note that the Blades dice mechanic provides noticeably different odds than the equivalent 2d6 rolls, so it’s worth talking about what effect you want the dice to have before deciding which pool mechanic might be right for your game.

As for adding extra dice to a pool, one of the features of dice pools is that additional dice provide diminishing returns so if you want to stack a lot of bonuses without breaking the game, dice pools could be the way to go.


@Airk I think as much as I hate to face it, you’re right both about failing those big rolls just being not fun, and about needing to be pretty lean with modifiers. I’m probably trying to have too much going on, for either system =/

Edit: I was gonna ask for feedback on another go at a system but I’ve had like five ideas since I asked and I clearly need to just keep noodling away on my own XD

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I… don’t entirely mean to discourage you from making it possible to fail big rolls, but somehow it feels better to me to fail a big roll because I was only allowed to stack bonuses up to a certain point than it does to fail a big roll after I scraped for every last advantage and built up a huge pile of dice? The former gives me a feeling of “Well, this is as good as it’s going to get, so time to trust to luck” while the latter gives me the feeling of “I did everything I possibly could and still failed”?

I still think that if you want to do something with a lot of modifiers, your best bet is to Flying-Circus it and use 2d10 or similar, so that the impact of each individual modifier is less; But having lots of modifiers has other perils, of course.

I’m surprised people are looking at this as such a open-and-shut case. There are lots of fun ways to mess around with dice pools to get granularity.

It’s true that “advantage” (rolling an extra die) has greater impact than a +1, so you won’t get more granularity that way. However, you can change the size of the dice you’re rolling, the way you determine the result, or the scale/ladder of results. For instance, if a “mixed success” is 10-11 and a 12 is a full success, you could roll a lot more dice and still get reasonable odds. 2d6, in that scheme, is pretty miserable (similar to, but slightly worse than, rolling at -2 in a PbtA game), and you can go up to about 10d6 before you get something equivalent to rolling with a +3.

I’ve fooled around with lots of different ways to make dice pools, work, though. For instance, take a look at page four in this draft document I put together for a hypothetical thought experiment of a game:

And, if you’re willing to mix die sizes, you can get all kinds of dice pool goodness. I should post some of my PbtA-style games that do this, like The Bureau or my rules for mixed dice types for Apocalypse World.


Here’s a twitter thread where he describes some of the mechanics:


Here’s a relatively clean way to do dice pools and diminishing returns in a PbtA range:

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