D&D Blog : Dice Tricks

[Herremann the Wise]

I see the 2d20 being a good way of simulating a character who is expert in what the dice roll is representing rather than luck (even though such a luck mechanic has been common enough in D&D). The adding of an additional die to a "core mechanic roll" just strikes my mathematical brain as being plain awkward as a core mechanic - even though I can see it being a reasonable representative of expertise.

I think swaying away from the core mechanic of a d20 roll plus modifier compared to a number (DC) would be an incredibly significant step and possibly a dangerous one; it's not going to really feel like I'm playing Dungeons & Dragons... at least to begin with.

Best Regards
Herremann the Wise

 

[Herremann the Wise]

I'm trying to work out where Monte got 4.5 from; my calculations indicate rolling 2d20 increases the average result by 3.325...

Hmm.

Weird that, the average is 13.825 which is a 3.325 increase.
I'm trying to work out where they would get a "15" from but at the moment, it is escaping me.

Best Regards
Herremann the Wise

 

[El Mahdi]

Another poorly done poll. The questions were written in a way as to support assumptions, rather than truly divine preferences. The last question was the worst. In a previous question you answer whether you feel Dice Tricks should be part of core, then the last question assumes you do want them in core (without options or answers to express that).

I wanted to be able to say on the last question that I don't want them in core, I do want them in the game (as a module), and I like both Dice Tricks as appropriate in different situations ("Both" was not an option).

I'm getting the impression that the designers are writing these question themselves.

I think that's a big mistake.

They should be, at the least, getting the advice of a real professional pollster. Or best case, hire a pollster to write their questions for them (after the pollster determines what information the designer is really looking for).

I'm afraid if they keep doing their polls this way, they are going to end up making decisions based on faulty or completely inaccurate data.

 

[Mercule]

I see the 2d20 being a good way of simulating a character who is expert in what the dice roll is representing rather than luck (even though such a luck mechanic has been common enough in D&D).

Could this be the answer to multiple attacks and/or weapon specialization? At 7th level, the fighter rolls 2d20 for all attacks and takes the better. At 14th level, he rolls 3d20 and keeps the best.

I could probably add some structure around that to make it feel more like multiple attacks or super-specialization, too. Maybe grant the bonus rolls for free and then have a feat tree or two to represent different focuses.

Power Attack
Prerequisite: two or more attack rolls.
Effect: Starting with the highest die rolled, compare the result to your target's AC. If only the highest result would hit, do normal damage. If the second highest roll would also hit, add a competence bonus equal to your strength bonus (1.5 str bonus for two-handed weapons) to the damage dealt.

Improved Power Attack
Prerequisite: Power Attack, three or more attack rolls.
Effect: As per Power Attack, plus if you have a third attack roll and it also would hit, the bonus increases to double your strength bonus (triple for two-handed weapons).

Whirlwind Attack
Prerequisite: two or more attack roles.
Effect: If your highest attack roll would hit your target, pick a second target you threaten. If your second highest attack roll would hit that target, that target takes half the damage you role against the primary target.

Improved Whirlwind Attack
Prerequisite: Whirlwind Attack, three or more attack rolls.
Effect: As per Whirlwind Attack, plus if the second attack hits, and you have a third attack roll, you may choose a tertiary opponent you threaten to compare this roll against. If it succeeds, this target also takes half the damage rolled.

Weapon Specialization
Prerequisites: proficiency in weapon, two or more attack roles.
Effect: If only your highest attack would hit your target, apply damage as normal. If your second highest attack would also hit, apply half your BAB (formula assumes 3e BAB) to the damage dealt.

Weapon Mastery
Prerequisites: Weapon Specialization in weapon, three or more attack roles.
Effect: As per Weapon Specialization, but if your second and third attacks also hit, you apply your full BAB to the damage dealt.

I have a couple ideas on Weapon Finesse and Two Weapon Fighting, but you get the point.

Edit: I'd also see the stylistic modes (power, whirlwind, finesse) being mutually exclusive, but specialization (and, maybe TWF) being additive. You could also add other feats allowing combinations, like:

Berserker
Prerequisites: Power Attack, Whirlwind Attack
Effect: The effects of Power Attack and Whirlwind attack are cumulative. Apply Power Attack damage to the first target before calculating damage to the secondary target.

 

[Hassassin]

Weird that, the average is 13.825 which is a 3.325 increase.
I'm trying to work out where they would get a "15" from but at the moment, it is escaping me.

Best Regards
Herremann the Wise

The 4.5 probably comes from the fact that the probability to make DC 10 with 2d20dl is between the probabilities of making it with 1d20+4 and 1d20+5.

 

[Harlekin]

I'm trying to work out where Monte got 4.5 from; my calculations indicate rolling 2d20 increases the average result by 3.325...

Hmm.

It depends on the DC. If you need an 11 to succeed, your probability with one die is 0.5, but with two dice it's 0.75, which is equivalent to DC 6. So for a DC 11 re-rolling is equivalent to a +5 modifier.
For comparison, for a DC 20 roll, re-rolling is less then a +1 modifier.

(By DC above, I mean target number after all other boni are taken into account)

 

[BryonD]

Many valid points already made.

Very often D20 isn't about degree of result but is a hit target number / missed target number issue. Aside from the simple math being done wrong, it was the wrong math to be doing.

Other than that....

 

[avin]

Short story: I love dice tricks.

Long story: Ilove dice tricks.

 

[Ardulac]

I'm trying to work out where Monte got 4.5 from; my calculations indicate rolling 2d20 increases the average result by 3.325...

Hmm.

As someone else already mentioned, the +5 is a result of the odds of success going up from .5 to .75, which works for 4E since the target difficulty seems to be about a 50/50 chance. It's a bit of an unfortunate choice for illustrating this idea since a 50/50 chance generates the absolute best benefit for the d20 re-roll (fun fact: if you know the DC, 2d20dl is the same as re-roll-take-the-new-roll because you would never re-roll a success). The equivalent benefit of re-rolling is chance of failure * (1 - chance of failure) * 20 [really you should divide by .05, but multiplying by 20 has the same effect since it is the inverse]. For example, a .75 chance to succeed would be .75 * .25 * 20 = +3.75.

As the first post pointed out, this disregards critical results and graduated success levels, but it works well for any single DC skill check, stat check, or saving throw. And if you want to include crits in the roll then you can normally just double the crit range to get pretty close to the same result even though technically the crit range should only be increased by +.95 if a 20 is required to crit and +.8 if a 19 is required to crit.

 

[Truename]

It depends on the DC. If you need an 11 to succeed, your probability with one die is 0.5, but with two dice it's 0.75, which is equivalent to DC 6. So for a DC 11 re-rolling is equivalent to a +5 modifier.
For comparison, for a DC 20 roll, re-rolling is less then a +1 modifier.

To expand on this, the chance of hitting is...

[B]DC[/B]    [B]1d20[/B]     [B]2d20[/B]    [B]Equivalent to +[/B]
2   95%   99.8%    1.0
3   90%   99.0%    1.8
4   85%   97.8%    2.6
5   80%   96.0%    3.2
6   75%   93.8%    3.8
7   70%   91.0%    4.2
8   65%   87.8%    4.6
9   60%   84.0%    4.8
10  55%   79.8%    5.0
11  50%   75.0%    5.0
12  45%   69.8%    5.0
13  40%   64.0%    4.8
14  35%   57.8%    4.6
15  30%   51.0%    4.2
16  25%   43.8%    3.8
17  20%   36.0%    3.2
18  15%   27.8%    2.6
19  10%   19.0%    1.8
20  5%     9.8%    1.0

...and the effective crit range is increased to 19-20. For builds that already crit on a 19, the effective crit range increases to 17-20.

(This doesn't account for automatic hits on 20 or automatic misses on 1.)