You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter EzequielPR
- Start date

Alas, it's not something I can recommend. But since I don't want to be "that guy", I'll leave it at that, and instead wish you the best of luck - I do hope it works out for you.

I'm open to any comment. As long as what you say is reasonable it's OK.

Well, okay. I didn't want to just dump on the idea.

Unfortunately, I don't think it works: D&D 3e, and by extension Pathfinder, are built assuming a linear probability, and switching to a bell curve doesn't work with that very well. As UA notes, bonuses to the roll become much more important, and in 3e/PF the bonuses get

Unfortunately, given the fundamental different assumptions in play, I'd actually be more inclined to find a new system entirely rather than try to retrofit 3d6 in place of the d20.

Remember that Im just curious about this optional rule, it's not that I really want it. If I see that there is no good in it I'll not use it.

Thanks for your opinion.

+4 or -4 is pretty common in D&D, changing the odds by 20%, but it moves "pretty likely" (10+; 62.5%) to "bit of a long shot" (14+, about 25% IIRC).

You could adjust all the bonuses and penalties to tighten them as well, but you're forced to rewrite a lot of the game.

I'll agree with you here, because watching people add up 3d6 when they could just be reading a d20 does feel very harsh. Now, as already mentioned, this doesn't work very well for 3.5 or Pathfinder because whole-point and multiple/sizable bonuses get exponential when compared to a bell curve contest roll. 5e is a little better, with the smaller numbers, and the Adv/Dis mechanic works exceptionally well with a bell curve contest.It sacrifices some randomness to gain a bit of realism. It makes me feel like every combat is harsh

Bottom line: you'd be better off leaving the bell curve in the system designed with it in mind: AGE.

How does 3d6 even work? if you're using a greataxe or bow you'll never hit 20 for a critical...

Further reflection: kiss Critical Hits goodbye unless you revamp those rules. a Nat 20 comes up 5% of the time on a d20. 19/18? 10%/15%.

An 18 on 3d6 is one in 216 (under 0.5%) and a 17 is 4 chances in 216 (so about 1.85%).

What are the chances of rolling two or more sixes on 3d6? Maybe crits could be linked to double-sixes instead.

7.4% = 16/216What are the chances of rolling two or more sixes on 3d6? Maybe crits could be linked to double-sixes instead.

Pretty reasonable. You could also require a hit for it to be a critical, which would lower it a bit.

Yes, getting a nat 20 would be rare, but in a bell curve, that's 2 or 3 standard deviations, so it should be.

If you are changing this on your players, you should tell them to almost never critical hit, and when it happens, it should be a pretty significant event ( more than double damage): like something from Prowlers and Paragons The player gets to narrate what happens

What are the chances of rolling two or more sixes on 3d6? Maybe crits could be linked to double-sixes instead.

Neat idea: in thinking about this and my 6d4-4 suggestion, you could also add a poker style element where bonuses come from poker type results: three-of-a-kind, full house, four-of-a-kind, two pairs....

I'm assuming "highest roll" as a potential critical and lowest as "always fails to hit or save", but you're right that you can't roll 1 or 20 at all. A lot of the rules would need to be revised.

GURPS excuse me or Hero System strike me as likely candidates. But translating D&D to these systems is likely to carry similar challenges.

GURPS excuse me or Hero System strike me as likely candidates. But translating D&D to these systems is likely to carry similar challenges.

Last edited:

7.4% = 16/216

Pretty reasonable. You could also require a hit for it to be a critical, which would lower it a bit.

Rolling a 13 (6-6-1) as a potential critical hit when a 16 (6-5-5) is not may offend the senses of anyone who wants "high roll = better roll) to be maintained, but it's a possible approach. Dealing with weapons that Crit on an 18 or 19+, and dealing with Improved Critical, will also need to be addressed.

Any and all of these issues CAN be addressed, but if the goal in doing so is to re-create similar probabilities, it will be a lot of work. What's the objective of making the change? Maybe some of these rules have to suffer marked probability changes, or even be removed entirely, to reach that goal. If the goal is "more predictable, less swingy results", that probably suggests removal of crit's rather than some new means of retaining them.

It does lead to an odd thing that the "value" of +1 ceases to be +5% and varies depending upon what number you want need to roll. I believe it gives the "most percentile" benefit when you need to roll a 10+ or 11+ on the 3d6.

Also could lead to very tiresome fights between high AC monsters and players trying to hit each other.

If you're rolling D20+4 to hit AC: 20 you hit on 16-20; so 20% chance or an average of one hit in five attacks.

If you're rolling 3d6+4 to hit AC: 20 you hit on 16-18: so 4.62% change, so on average less than one hit in twenty attacks.

**Threat Range Maths! Wheee!**

The other thing is critical threat ranges (and similar) need adjusting to accommodate the new probabilities.

Rolling a D20 has 20 different possibilities, rolling 3d6 leads to 216 different ways the dice can fall.

This is useful for corresponding probabilities.

http://www.thedarkfortress.co.uk/tech_reports/3_dice_rolls.htm#.VpMFpxWLS70

I believe

3d6

18= 0.46%

17-18 = 1.85%

16-18 = 4.62%

15-18 = 9.25%

14-18 = 16.20%

13-18 = 25.92%

12-18 = 37.50%

11-18 = 50%

Compared to the rather simpler:

20 = 5%

19-20 = 10%

18-20 = 15%

17-20 = 20%

16-20 = 25%

15-20 = 30%

Which actually is a lot better mapping than I first guessed

(although 17-20 is awkward)

So equivalence:

"Natural 20" = "Natural 16-18"

"Natural 19-20" = "Natural 15-18" (Long Swords/Short Swords etc)

"Natural 18-20" = "Natural 14-18" (Rapiers)

"Natural 17-20" = Uh "Natural 14-18 and flip a coin with a natural 13?"

"Natural 16-20" = "Natural 13-18"

"Natural 15-20" = Again somewhat awkward "Natural 13-18 and flip a coin with a natural 12?"

Similarly a "Natural 1" on a D20 has similar probabilities to "Natural 3-5"

Apparently Improved Critical/Keen Weapons helpfully get Critical threats into the awkward numbers "A threat range of 20 becomes 19-20, a threat range of 19-20 becomes 17-20, and a threat range of 18-20 becomes 15-20."

Also could lead to very tiresome fights between high AC monsters and players trying to hit each other.

If you're rolling D20+4 to hit AC: 20 you hit on 16-20; so 20% chance or an average of one hit in five attacks.

If you're rolling 3d6+4 to hit AC: 20 you hit on 16-18: so 4.62% change, so on average less than one hit in twenty attacks.

The other thing is critical threat ranges (and similar) need adjusting to accommodate the new probabilities.

Rolling a D20 has 20 different possibilities, rolling 3d6 leads to 216 different ways the dice can fall.

This is useful for corresponding probabilities.

http://www.thedarkfortress.co.uk/tech_reports/3_dice_rolls.htm#.VpMFpxWLS70

I believe

3d6

18= 0.46%

17-18 = 1.85%

16-18 = 4.62%

15-18 = 9.25%

14-18 = 16.20%

13-18 = 25.92%

12-18 = 37.50%

11-18 = 50%

Compared to the rather simpler:

20 = 5%

19-20 = 10%

18-20 = 15%

17-20 = 20%

16-20 = 25%

15-20 = 30%

Which actually is a lot better mapping than I first guessed

(although 17-20 is awkward)

So equivalence:

"Natural 20" = "Natural 16-18"

"Natural 19-20" = "Natural 15-18" (Long Swords/Short Swords etc)

"Natural 18-20" = "Natural 14-18" (Rapiers)

"Natural 17-20" = Uh "Natural 14-18 and flip a coin with a natural 13?"

"Natural 16-20" = "Natural 13-18"

"Natural 15-20" = Again somewhat awkward "Natural 13-18 and flip a coin with a natural 12?"

Similarly a "Natural 1" on a D20 has similar probabilities to "Natural 3-5"

Apparently Improved Critical/Keen Weapons helpfully get Critical threats into the awkward numbers "A threat range of 20 becomes 19-20, a threat range of 19-20 becomes 17-20, and a threat range of 18-20 becomes 15-20."

Last edited:

Spot on: and this is the main reason that the 3d6 method sucks bananas big time.Also could lead to very tiresome fights between high AC monsters and players trying to hit each other.

If you're rolling D20+4 to hit AC: 20 you hit on 16-20; so 20% chance or an average of one hit in five attacks.

If you're rolling 3d6+4 to hit AC: 20 you hit on 16-18: so 4.62% change, so on average less than one hit in twenty attacks.

- Replies
- 15

- Views
- 5K

- Locked

- Replies
- 374

- Views
- 16K

- Replies
- 0

- Views
- 500

- Replies
- 4

- Views
- 5K

- Replies
- 23

- Views
- 1K