bell curve rolls [Archive] - Wizards Community

bell curve rolls [Archive] - Wizards Community

Post/Author/DateTime Post
Patera_Quetzal
03-12-07, 09:56 AM I like the bit from Unearthed Arcana on bell curve rolls, but the 3d6 curve seems too steep to me, and I don't like the fact that you can only roll up to 18. Besides, "natural 18" happens on 0.46% of rolls, making it virtually unheard of. You can fix the 18 ceiling problem by rolling 2d6 + 1d8, but then a natural 20 is even less rare -- 0.35% chance if my math is right -- and the curve is still very steep. Has anyone experimented with variants on this system? I have an idea about this: roll 2d10 instead.

Rolling 2d10 obviously gives you 100 possible rolls, giving you a 1% chance of "snake-eyes" (or double-10s). This may still be too low for you, so you could rule that automatic miss occurs on 2 and 3 (auto-hit on 19 and 20) which gives a 3% chance. Rolling 2, 3, or 4 (or 18, 19, or 20) has a 6% probability, which is fairly close to the 5% chance of rolling 1 (or 20) on a d20.

The average roll on 2d10 is 11, which is higher than the 10.5 average on 3d6. 44% of rolls on 2d10 are between 9 and 13, versus 25% on 1d20, or 56% on 3d6. Does this interest anyone? Is my math right? (I’m a musician.)

An alternative to this is to roll 1d12+1d8, which gives 96 possible rolls and therefore a slightly higher chance of 2 or 20.

(Bell curve rolls could also be used on the variable modifiers, but this would eliminate some of the “variability,” one presumably desires from this rule, and if you’re using bell curves on both the rolls and the modifiers you could end up rolling a whole lot of dice.)
kenicolo
03-12-07, 07:28 PM I believe that the use of the bell curver of 2D10 could easyly be a feat.

so if a character need mor stability in his rolls like an IMPROVE SKILL FOCUS would ben nice. If you like it mor powerful lets say ROLL 3D10 and discard the lowest! i dont know the math about this but i see it in another RPG where it was called Natural aptitude
RobbyPants
04-11-07, 02:44 PM All in all, 2d10 and 3d6 should both work very well in the standard d20 game. Both 3d6 and 1d20 have an average of 10.5 (which is what so much of the 10 + mods mechanic comes from). The average of 2d10 is 11, so it will set the power level just slightly higher, but that shouldn't be a problem, because both PCs and NPCs will be rolling this way.

Obviously, 2d10 is a nice middle ground for 3d6 and 1d20. It still has the bell-curve effect, but not so much as 3d6, and it is not nearly as random as 1d20. I imagine you've read all the background in the 3d6 section of UA? I would figure the same rules apply here, but to a lesser extent. Like, a character's power will be more focused on their modifies and less on the actual rolls.

As for "natural 20" equivalents, I'd try:

d20 % 2d10 %

20 5% 18+ 6%
19+ 10% 17+ 10%
18+ 15% 16+ 15%
17+ 20% 15+ 21%
15+ 30% 14+ 28%
1 5% 2-4 6%
trapspringer
04-11-07, 02:55 PM What about a trait?

The upside is you usually roll 10.5, and you'll never see a 1.

The downside is you practically never roll over a 17.

No criticals, no spectacular successes, etc.

The only problem is every rogue in the world would take that trait.
UAMDB
04-11-07, 03:03 PM I have played in games that use the 2d10 rule. It was one of the worst games I have every played. It just did not have the feel that I was use to. But they also used alot of wierd house rules. I would never use it in my games, and I will not play in another game that uses it again.

It was like I was taking ten for every thing.
RobbyPants
04-11-07, 03:49 PM What about a trait?

The upside is you usually roll 10.5, and you'll never see a 1.

The downside is you practically never roll over a 17.

No criticals, no spectacular successes, etc.

The only problem is every rogue in the world would take that trait.
Sort of. It does put most rolls (49%) in the 9 - 13 range, but it is still possible to roll higher or lower. That is why I created the following table to expand the range. The idea is with a d20, you have a 5% chance to roll a natural 1. On 2d10, the best equivalent is to treat a 2-4 (6%) as a natural 1. I also included some other numbers, to simulate threat ranges for weapons. Obviously you'll only roll a natural 20 1% of the time, so you have to treat an 18-20 (6%) as a natural 20.

d20 % 2d10 %

20 5% 18+ 6%
19+ 10% 17+ 10%
18+ 15% 16+ 15%
17+ 20% 15+ 21%
15+ 30% 14+ 28%
1 5% 2-4 6%

I have played in games that use the 2d10 rule. It was one of the worst games I have every played. It just did not have the feel that I was use to. But they also used alot of wierd house rules. I would never use it in my games, and I will not play in another game that uses it again.

It was like I was taking ten for every thing.
Yeah, the bell curves pretty much do that. I don't use them, because I feel that combat is supposed to be chaotic and random. The high and low results of attack rolls and saves (to me) represent all the little things like losing your balance, dropping your guard, and about a million other tiny factors. The bell curve system puts almost all the focus on your modifiers, and less on your rolls.

Post/Author/DateTime	Post
Patera_Quetzal 03-12-07, 09:56 AM	I like the bit from Unearthed Arcana on bell curve rolls, but the 3d6 curve seems too steep to me, and I don't like the fact that you can only roll up to 18. Besides, "natural 18" happens on 0.46% of rolls, making it virtually unheard of. You can fix the 18 ceiling problem by rolling 2d6 + 1d8, but then a natural 20 is even less rare -- 0.35% chance if my math is right -- and the curve is still very steep. Has anyone experimented with variants on this system? I have an idea about this: roll 2d10 instead. Rolling 2d10 obviously gives you 100 possible rolls, giving you a 1% chance of "snake-eyes" (or double-10s). This may still be too low for you, so you could rule that automatic miss occurs on 2 and 3 (auto-hit on 19 and 20) which gives a 3% chance. Rolling 2, 3, or 4 (or 18, 19, or 20) has a 6% probability, which is fairly close to the 5% chance of rolling 1 (or 20) on a d20. The average roll on 2d10 is 11, which is higher than the 10.5 average on 3d6. 44% of rolls on 2d10 are between 9 and 13, versus 25% on 1d20, or 56% on 3d6. Does this interest anyone? Is my math right? (I’m a musician.) An alternative to this is to roll 1d12+1d8, which gives 96 possible rolls and therefore a slightly higher chance of 2 or 20. (Bell curve rolls could also be used on the variable modifiers, but this would eliminate some of the “variability,” one presumably desires from this rule, and if you’re using bell curves on both the rolls and the modifiers you could end up rolling a whole lot of dice.)
kenicolo 03-12-07, 07:28 PM	I believe that the use of the bell curver of 2D10 could easyly be a feat. so if a character need mor stability in his rolls like an IMPROVE SKILL FOCUS would ben nice. If you like it mor powerful lets say ROLL 3D10 and discard the lowest! i dont know the math about this but i see it in another RPG where it was called Natural aptitude
RobbyPants 04-11-07, 02:44 PM	All in all, 2d10 and 3d6 should both work very well in the standard d20 game. Both 3d6 and 1d20 have an average of 10.5 (which is what so much of the 10 + mods mechanic comes from). The average of 2d10 is 11, so it will set the power level just slightly higher, but that shouldn't be a problem, because both PCs and NPCs will be rolling this way. Obviously, 2d10 is a nice middle ground for 3d6 and 1d20. It still has the bell-curve effect, but not so much as 3d6, and it is not nearly as random as 1d20. I imagine you've read all the background in the 3d6 section of UA? I would figure the same rules apply here, but to a lesser extent. Like, a character's power will be more focused on their modifies and less on the actual rolls. As for "natural 20" equivalents, I'd try: d20 % 2d10 % 20 5% 18+ 6% 19+ 10% 17+ 10% 18+ 15% 16+ 15% 17+ 20% 15+ 21% 15+ 30% 14+ 28% 1 5% 2-4 6%
trapspringer 04-11-07, 02:55 PM	What about a trait? The upside is you usually roll 10.5, and you'll never see a 1. The downside is you practically never roll over a 17. No criticals, no spectacular successes, etc. The only problem is every rogue in the world would take that trait.
UAMDB 04-11-07, 03:03 PM	I have played in games that use the 2d10 rule. It was one of the worst games I have every played. It just did not have the feel that I was use to. But they also used alot of wierd house rules. I would never use it in my games, and I will not play in another game that uses it again. It was like I was taking ten for every thing.
RobbyPants 04-11-07, 03:49 PM	What about a trait? The upside is you usually roll 10.5, and you'll never see a 1. The downside is you practically never roll over a 17. No criticals, no spectacular successes, etc. The only problem is every rogue in the world would take that trait. Sort of. It does put most rolls (49%) in the 9 - 13 range, but it is still possible to roll higher or lower. That is why I created the following table to expand the range. The idea is with a d20, you have a 5% chance to roll a natural 1. On 2d10, the best equivalent is to treat a 2-4 (6%) as a natural 1. I also included some other numbers, to simulate threat ranges for weapons. Obviously you'll only roll a natural 20 1% of the time, so you have to treat an 18-20 (6%) as a natural 20. d20 % 2d10 % 20 5% 18+ 6% 19+ 10% 17+ 10% 18+ 15% 16+ 15% 17+ 20% 15+ 21% 15+ 30% 14+ 28% 1 5% 2-4 6% I have played in games that use the 2d10 rule. It was one of the worst games I have every played. It just did not have the feel that I was use to. But they also used alot of wierd house rules. I would never use it in my games, and I will not play in another game that uses it again. It was like I was taking ten for every thing. Yeah, the bell curves pretty much do that. I don't use them, because I feel that combat is supposed to be chaotic and random. The high and low results of attack rolls and saves (to me) represent all the little things like losing your balance, dropping your guard, and about a million other tiny factors. The bell curve system puts almost all the focus on your modifiers, and less on your rolls.