3d6 Bell Curve rolls

[tedcahill2]

It just occurred to me that this variant, which is from Unearth Arcana, doesn't change any of the DC for skill checks or anything like that.

So a DC 15 skill check goes from having a 30% success from a good die roll alone, to much much less.

Do you think this was intentional? Or should the DC's be adjusted to keep the same % success chance from die rolls only (such as DC 15's on 1d20 being approx. equal to a DC 12 on 3d6)?

[johnbragg]

It just occurred to me that this variant, which is from Unearth Arcana, doesn't change any of the DC for skill checks or anything like that.

So a DC 15 skill check goes from having a 30% success from a good die roll alone, to much much less.

Do you think this was intentional? Or should the DC's be adjusted to keep the same % success chance from die rolls only (such as DC 15's on 1d20 being approx. equal to a DC 12 on 3d6)?

IT's intentional. IT's the whole point of 3d6 vs d20. The idea is to give the probabilities a hard shift towards the 8-12 range. Chances of success are driven by the modifiers to the roll--skill ranks, BAB, situational modifiers, Aid Another, luck spells, etc.

So yes, using 3d6, a DC 5 skill check with no bonuses to the roll succeeds 98% of the time, a DC 10 check succeeds 62% of the time, a DC 15 succeeds 9% of the time. According to Anydice.com

I'd like to run something where Rogues have the inherent property of being able to choose what they roll, 3d6 or d20. (See Haley's speech where she deduces that Xykon isn't any of the visible skeletons.)

[Zanos]

The purpose of 3d6 is to make extremes less likely, which means your modifier to the check matters more.

If you have +0 to a DC 15 check:
1d20: has a 25% chance of passing.
3d6: has a 9.26% chance of passing.

If you have a +5 to a DC 15 check:
1d20: has a 50% chance of passing.
3d6: has a 50.92% chance of passing.

If you have +10 to a DC 15 check:
1d20: has a 75% chance of passing.
3d6: has a 95.37% chance of passing.

Since average results are heavily favored with the bell curve, characters are unlikely to succeed at tasks they are bad at, but more likely to succeed at tasks they are skilled at. If you prefer to emphasize skill over luck, the bell curve system works rather well. You have to tweak crit ranges, though.

[Gildedragon]

Yup. I love this variant tbh

[Ellrin]

It feels a little too much like taking 10, to me, though I'll grant that I tend to favor dependably average results over a completely random spread.

[Pleh]

It feels a little too much like taking 10, to me, though I'll grant that I tend to favor dependably average results over a completely random spread.

Actually, that could be a fun hybrid: take 3d6.

Any time you could normally take 10, you may use 3d6 in place of your d20 (subject to the same restrictions as taking 10)

[Lvl 2 Expert]

Yeah, the point of a distribution like this is to make people enjoy being skilled more.

You're third level characters, and your rogue has 6 skill ranks and a +2 ability bonus in most of her important skills. This means she has about a 40% better change of making any one check than any of the party members who haven't ever done anything with that skill. She can still fail at relatively easy tasks and when she does some other party member will often try it, with a decent chance of succes. In 3D6 the rogue will be able to complete those same relatively easy tasks much more reliably, while they are quite hard for anyone unskilled. It feels more like skill ranks mean something. And if the harder tasks become to hard you can always re-calibrate the DC's a little, this will benefit the most skilled characters the most.

The counter to this argument is that exactly the opposite can be fun as well. The fighter is not trained in athletics or use rope (yes, this example takes place in a weird hybrid system), but the bad guy is getting away along the balustrade, and that chandelier in the middle of the room is just asking to be swung on. D20 encourages the fighter to just go for it, he has a chance of succes, with 3D6 he'd probably just run after the guy the long way around.

So it's really up to personal preference, which style you like. It's a little like prepared VS spontaneous casting. One allows you to use what you have more proficiently, the other allows you to improvise more. A middle ground could be 2D10/2D12/1D12+1D8 etc, any two dice option will give a curve somewhere between 1 die and 3 dice. If the dice are unequal you'll even get a flat plateau in the middle of the distribution with diminishing odds only along the sides.

[heavyfuel]

It's actually impossible to keep the percentage of success

With 0 modifier in a skill, a DC 15 check has 30% of chance to happen using 1d20, and around 9% with 3d6
With 6 points in a skill (4 ranks and 2 ability bonus), it goes to 55% using 1d20, and 74% using 3d6

See why it's impossible? Having a slightly bigger or smaller modifier has a much bigger impact on success rate

If you try to maintain that 30% chance of success, you'd have to make it a DC 13 (26% chance of success) or DC 12 (37% chance). However, by the time anyone invests a little in this skill, the DC 12 or 13 is now incredibly easy to achieve.

Still, I suggest you give the system a try for a few sessions if you want a game that isn't so up to chance. After some experimentation, I discovered that my favourite use for this is to use 3d6 for everything except attack rolls, which still use 1d20.

[Gildedragon]

Yeah, the point of a distribution like this is to make people enjoy being skilled more.

You're third level characters, and your rogue has 6 skill ranks and a +2 ability bonus in most of her important skills. This means she has about a 40% better change of making any one check than any of the party members who haven't ever done anything with that skill. She can still fail at relatively easy tasks and when she does some other party member will often try it, with a decent chance of succes. In 3D6 the rogue will be able to complete those same relatively easy tasks much more reliably, while they are quite hard for anyone unskilled. It feels more like skill ranks mean something. And if the harder tasks become to hard you can always re-calibrate the DC's a little, this will benefit the most skilled characters the most.

The counter to this argument is that exactly the opposite can be fun as well. The fighter is not trained in athletics or use rope (yes, this example takes place in a weird hybrid system), but the bad guy is getting away along the balustrade, and that chandelier in the middle of the room is just asking to be swung on. D20 encourages the fighter to just go for it, he has a chance of succes, with 3D6 he'd probably just run after the guy the long way around.

So it's really up to personal preference, which style you like. It's a little like prepared VS spontaneous casting. One allows you to use what you have more proficiently, the other allows you to improvise more. A middle ground could be 2D10/2D12/1D12+1D8 etc, any two dice option will give a curve somewhere between 1 die and 3 dice. If the dice are unequal you'll even get a flat plateau in the middle of the distribution with diminishing odds only along the sides.

Also adding hero points to the system is handy, for things like chandelier swinging amd the like

[Lvl 2 Expert]

Also adding hero points to the system is handy, for things like chandelier swinging amd the like

That would be a nice compromise. You get the more realistic curve, but a few times a day when lives are in the balance and a plan comes up so crazy it has to work the player can get a bonus/an extra die/advantage/a D20/something. It's a bit of a dissociated mechanic, it's hard to say in universe why you can do something a little better exactly 4 times per short rest, but it does provide both the 3D6 and the D20 types of fun.

[johnbragg]

Also adding hero points to the system is handy, for things like chandelier swinging amd the like

Hero Points let you roll 4d6 instead of 3d6, right? :smallwink:

[Zanos]

The counter to this argument is that exactly the opposite can be fun as well. The fighter is not trained in athletics or use rope (yes, this example takes place in a weird hybrid system), but the bad guy is getting away along the balustrade, and that chandelier in the middle of the room is just asking to be swung on. D20 encourages the fighter to just go for it, he has a chance of succes, with 3D6 he'd probably just run after the guy the long way around.
Probably a bad example, since the Fighter is probably wearing armor and his chance of making an untrained balance check with an ACP and probably low dex is really, really bad in either system.

But in general, yeah. 3d6 means that if you aren't invested in something, your chances of making any but the most basic of checks is extremely low.

[Lvl 2 Expert]

Probably a bad example, since the Fighter is probably wearing armor and his chance of making an untrained balance check with an ACP and probably low dex is really, really bad in either system.

But in general, yeah. 3d6 means that if you aren't invested in something, your chances of making any but the most basic of checks is extremely low.

Sure, but still, many DM's will even go with the optional ruling that a 20 is an automatic succes, and that's still a 1/20 shot, and better than the odds of rolling either 18, 17 or 16 using 3D6.

But yeah, point taken.

[tedcahill2]

I haven't heard of hero points, but I actually was going to use something that, as far as I know, is of my own design.

Each character will have a daily dice pool, per attribute, with a number of d6 equal to their ability modifier. They can use dice from the pool anytime they are making a roll using the associated ability. So your Dex dice pool has to be used when doing Dex related tasks, like firing a bow or balancing on a rope. You roll the normal 3d6+1d6 per dice pool die used, and keep the high 3.

[daryen]

Each character will have a daily dice pool, per attribute, with a number of d6 equal to their ability modifier. They can use dice from the pool anytime they are making a roll using the associated ability. So your Dex dice pool has to be used when doing Dex related tasks, like firing a bow or balancing on a rope. You roll the normal 3d6+1d6 per dice pool die used, and keep the high 3.

A suggestion, if you don't mind: this is a rare resource and heroic fantasy. Let them use all 4 dice.

[Crake]

Probably a bad example, since the Fighter is probably wearing armor and his chance of making an untrained balance check with an ACP and probably low dex is really, really bad in either system.

But in general, yeah. 3d6 means that if you aren't invested in something, your chances of making any but the most basic of checks is extremely low.

I feel like jumping to a chandelier and swinging across isn't balance at all, you're relying on your arm strength to catch the chandelier and hold on (and holding onto something isn't really balancing), and your core strength to add swing to the chandelier, along with your momentum from the jump to swing across to the other side, so I'd probably call it a climb check instead. Still has ACP, but it's now a class skill and a key ability score for the fighter.