D&D 5E Using 3d6 for skill checks

[phantomK9]

This is something I've thought a lot about. I've come up with several alternate dice methods that I have yet to fully try out:


Method 1:
Always roll 3d20.

• After rolling the dice, drop the highest die and the lowest die. Use the remaining d20 for the result.
• Under "Advantage", drop the two lowest dice and use the remaining d20 for the result.
• Under "Disadvantage", drop the two highest dice and use the remaining d20 for the result.
• Critical hits (and misses) are obtained as usual, but at least two dice must roll a 20 (or 1).

Method 2:
Replace the d20 with 2d10.

• After rolling, add the two dice together to get the result.
• Under "Advantage", add another d10. After rolling, drop the lowest die and add the two remaining dice together.
• Under "Disadvantage", add another d10. After rolling, drop the highest die and add the two remaining dice together.
• To keep odds of rolling a critical hit similar to standard d20, change the critical hit number from 20 to 18-19. Have a 20 be something extra special like free advantage with next attack as well as critical hit damage.
• Conversely a critical miss is achieved on a 3-4 with a roll of 2 being something especially heinous.

Option: Combine this with the Proficiency bonus as bonus die option from the DMG, although this will most likely necessitate a change in the critical hit/miss rules.


Method 3:
Always roll 4d10.

• After rolling, drop the highest die and the lowest die, add the remaining two dice together for the result.
• Under "Advantage" drop the two lowest dice and add together the two remaining dice for the result.
• Under "Disadvantage" drop the two highest and add together the two remaining two dice for the result.
• Critical should be achieved on a final result of 18-19 with a final result of 20 being extra special.
• Conversely a critical miss is achieved on a 3-4 with a roll of 2 being something especially heinous.

 

[robus]

The criticals are exactly the reason why I only used it for skill/ability checks and not for combat. Personally, I don't use "critical success" or "critical failure" on ability checks... so losing more 1s/20s due to using 2d10 will not actually matter.

On the other hand, critical success/failure on ability checks is an easy way to slip in the SWRPG feature of triumph and despair. So that your success or failure means that something interesting beyond the basic result of your action could be introduced by the DM.

 

[robus]

In the case of a weak wizard being able to move a boulder and a strong fighter failing I think what I call a Party Roll would make sense.

Surely only if the party declares "we try to move the boulder" ? And then it would be a group check as in the dmg...?

 

[Mercule]

I'd actually say it's less swingy because it is more likely that character with bonuses succeeds. It levels out the game on the side of successes. That might not be to your taste, but the math facts of 3d6 vs d20 say that 3d6 will have less variance and so be, by definition, less swingy.

I don't think I agree. If we were talking about a game without bonuses, then yes. D&D has bonuses that can stack up pretty quickly, exceeding the standard deviation of the bell curve. If you're already above the hump, it's not a big deal. If you're below, though, you suddenly get even more bang out of each bonus.

I could be wrong. I really don't have the time to run a full statistical analysis, even though I think it'd be fascinating.

What I suspect would happen is that the PCs would hit even more often than they do now -- monsters are generally balanced by hit points, not AC. Meanwhile, monsters would miss more often -- even my casual players have annoyingly high armor classes. The net is to reduce the difficulty of medium to easy foes and (potentially) increase the difficulty of hard and extreme foes, throwing the idea of bounded accuracy out the window.

Also, close to 50% of all possibilities will come up with four results (9, 10, 11, 12) and almost 70% fit into six results (8, 9, 10, 11, 12, 13). For two 1st level characters, one with proficiency and one without, you end up with the sort of "skilled characters are skilled" result you presumably want. By the time you hit 10th level, proficiency ends up being a +35% bonus. That assumes a "fair" challenge is balanced at an average roll succeeding, whether you center it on proficient or non-proficient attempts. If you center it between the two, then you get the full peak of the bell curve and the bonus goes up. You might as well say "You succeed if you're proficient". There's no point in Expertise. If you start including easy modifiers, like bless, enhance ability, magic weapons, etc. things get worse.

In retrospect, what I really meant by "swingy" wasn't so much random in the specific sense. It was more in the sense that any given challenge is likely to be either auto-success or auto-fail. Again, I haven't actually run the numbers. If your play experience is different, that's cool. I just have a very, very bad gut reaction to applying 3d6 to D&D. I think 2d10 might be a shallow enough curve to split the difference, but I'm not sure.

 

[Jeff Carlsen]

I'm all for 3d6. The one thing I dislike about the d20 system is the d20. I mean, I love the die itself, but such a large linear curve feels too unpredictable. I much prefer a strong bell curve.

I also like that 3d6 lines up with old-school ability score generation.

But I agree that DCs and ACs might need to be adjusted. Though with 3d6, perhaps AC should be replaced with a defense roll.

 

[Mercule]

Thanks for all your replies, folks.

Let me start by clarifying that we only use 3d6 for ability/skill checks, and not combat or saving throws. I think the flat distribution of 1d20 works just fine for combat, since combat is supposed to be frenetic and random and everyone rolls dice much more often with the PCs all having similar to hit bonuses.

However, skill/ability checks are made less often and more usually hinges on each individual roll than in combat. Social scenes often turn on a single Charisma check, for instance. We've found that it suits our play style to have the characters reliably be able to shine in their areas of expertise and struggle if they stray outside those areas.

A couple of issues people have raised have been in line with our experience. Firstly, the impact of advantage/disadvantage is reduced mathematically, and that’s something we’ve noticed. This hasn’t been a big deal for us though, since we rarely use advantage/disadvantage for skill checks, but I imagine it could be more of an issue in other games.

Also, as you’d expect, ability/skill checks can become rather predictable. This isn’t to everyone’s tastes, of course, but for us it’s a feature rather than a bug. Outliers can still happen, and to add a bit of further uncertainty to the process, we’ve given results of 3-5 and 16-18 special outcomes (with 3 and 18 being particularly dramatic).

As many of you have pointed out, it would be easy to dial the bell curviness up or down by using 2d10 or 4d4 or whatever. I think 3d6 works well for us, but I would be interested to hear of anyone using something else.

And if anyone has used something other than 1d20 at higher levels I’d be very interested to hear what they have to say.

I think applying only to skills would reduce a lot of my concerns. I still have them, but combat was the big one -- and where my previous conversations on the matter have led.

As you say, it's a style thing. I could see the allure of making it more reliable. I probably wouldn't want to go more than 2d10, though.

 

[ProphetSword]

One thing you can do to make the d20 system less swingy and to give the advantage back to people who have a proficiency in a skill is to quit relying on a single roll to equal success. When doing a skill check, have players roll 3d20 (if you're going to be rolling 3 dice anyway, might as well make them d20s). Instead of adding the numbers, add up the number of successes. For most skills, getting 2 out of 3 successes means that you succeed. For difficult tasks, make it 3 out of 3.

This has the effect of making characters who have proficiency in a skill succeed more often than those who don't, and will tip the balance back in their favor. You will still have cases where a character will get lucky, but there's room for luck on occasion, as it does happen in real life sometimes.

 

[happyhermit]

One thing you can do to make the d20 system less swingy and to give the advantage back to people who have a proficiency in a skill is to quit relying on a single roll to equal success. When doing a skill check, have players roll 3d20 (if you're going to be rolling 3 dice anyway, might as well make them d20s). Instead of adding the numbers, add up the number of successes. For most skills, getting 2 out of 3 successes means that you succeed. For difficult tasks, make it 3 out of 3.

This has the effect of making characters who have proficiency in a skill succeed more often than those who don't, and will tip the balance back in their favor. You will still have cases where a character will get lucky, but there's room for luck on occasion, as it does happen in real life sometimes.

That is interesting, but how do you factor adv/dis? I am not sure if that would work for me.

 

[ProphetSword]

That is interesting, but how do you factor adv/dis? I am not sure if that would work for me.

Could try this:

Advantage = One automatic success (so you only need 1 success out of 3)
Disadvantage = Require one additional success (so you need 3 out of 3)


This would mean that people who are really skilled would succeed more frequently even with disadvantage than people who are not skilled.

 

[happyhermit]

Could try this:

Advantage = One automatic success (so you only need 1 success out of 3)
Disadvantage = Require one additional success (so you need 3 out of 3)


This would mean that people who are really skilled would succeed more frequently even with disadvantage than people who are not skilled.

It is interesting, don't really like the automatic success part for some reason. Will think about it. It feels very different to me (breaking the check down into parts) and I don't feel it would work well for our combat, but it is interesting. It could work especially well in situations where partial success makes sense. Rather than having multiple checks, they could be combined to some degree.