The Next Mechanics -- Part 2: Re-"role"-ing the Dice

Somewhat in the same vein of a recent post, today I'm going to share some design ideas I've had recently, which may or may not appear in a future game.

First, I want to talk about class dice bonuses. Basically, I think an interesting basis for a new system would be to have simplistic d4, d8, and d12 attack bonuses, with d6 and d10 used strictly for extra damage; this obviously would be a lot easier to balance and mix-and-match in a design ethos which expressly isn't about "class dice," in the way that TNP is. 

That being said, I actually did manage to come up with some balanced reworks, whereby the dice bonuses are approximately equal (when using the assumption of 1d8 as the base damage.) These mechanics assume the dice bonuses can be added to attack AND damage, unless otherwise noted:

• d4: always treated as max value for the damage portion of the bonus; if the d4 ties the attack roll, treat the attack as a crit
• d6: [can be added to attack and damage] -- no other special considerations
• d8: if the d8 ties the attack roll, treat the attack as a crit; can only be added to a miss [essentially the same as the TNP bonus, with the addition of being able to be used for attack and damage]
• d10: roll 2d10, and use the total OR the d20 result to resolve the attack; treat the lower d10 result as the bonus damage, with mastery applied to the roll for determining the damage portion only
• d12: can be used in place of the attack roll; if the d12 roll ties the d20 roll and both would be a hit, treat the attack as a crit; if the d12 and d20 are a tie and both would miss, treat the attack as a hit

Some of these are obviously a bit wordy/clunky, so I do generally prefer the idea of streamlining the bonuses to be more simple, and at the same time making it so not all dice have to be bonuses.

The other major idea I've been giving some consideration to, is what is the resolution mechanic (if not d20)? The thing to ask is whether the DC10/d20 system is really adequate; to wit, is a 50% hit + 5% crit rate enough? Evidently not, since the design has needed to be reworked to include dice bonuses as well as combat mastery. My sense is that at the low end, a meaningful chance of success shouldn't drop below about 20%-25%, whereas at the high end, a meaningful chance of failure shouldn't be less than around 15%-20%

So let's look at some options, for success rates vs. DC10:

• 3d6: 62.50%
• 2d10: 64.00%
• 2d6+3: 58.22% 
• 1d6+1d10: 45%

You'll notice I included that last one, since it's the mechanic that TNP uses for skills; when you apply advantage to the d10 portion, the success rate increases to 66.83% or decreases to 23.17% with disadvantage. The 2d6 expression is meant to model "what if we replaced the 3rd d6 with something like an ability modifier?"
So what happens with the other mechanics? Let's say they all use the same idea of "highest/lowest [X-1] of XdY" as sort of an "advantage/disadvantage" mechanic.

• 3d6: 82.48% / 38.35%
• 2d10: 84.60% / 37.80%
  
• 2d6+3: 80.56% / 31.94%

Now, it's here I'll say that I think I can rule out the d10, for a couple of reasons. First, if we were to add something like a +1 modifier to it, the success rate would become too high. The other reason is that "roll 3d10 and keep the 2 highest" sort of loses the ergonomics of a straightforwardly 2d10 advantage/disadvantage mechanic, such as the one used for skills in TNP.

So what happens if we apply some kind of an "ability" modifier to the d6 candidates?

• 3d6+1: 89.51% / 51.23% (74.07% normal)
• 3d6+0: 82.48% / 38.35% (62.50% normal)
• 3d6-1: 73.07% / 26.93% (50.00% normal)
• 3d6-2: 61.65% / 17.52% (37.50% normal)
  
  
• 2d6+4: 89.35% / 47.69% (72.22% normal)
• 2d6+3: 80.56% / 31.94% (58.22% normal)
• 2d6+2: 68.06% / 19.44% (41.57% normal)
• 2d6+1: 52.31% / 10.65% (27.78% normal)

We find a couple of things:
3d6+1 is pretty comparable to 2d6+4, but both are a little high, with advantage applied.
3d6+0 and 2d6+3 are both kind of in the sweet spot, for all three expressions.
3d6-1 is definitely workable -- but at 2d6+2, disadvantage is at risk of taking the numbers too low.

Overall, the math makes me lean towards 3d6... but having modifiers that scale from -2 only to +1 is a little bit unconventional. The 2d6 mechanic being based around having only positive modifiers is intriguing, but at the far ends of that scale, it starts to flounder; advantage on 2d6+4 is really high, and disadvantage on 2d6+1 is really low.

I think if I were to use either of those for combat, I might consider using the existing TNP mechanic for skills -- otherwise, the obvious temptation is to just build the entire system out of d6s. Having a skill mechanic that at least uses d6 and d10 would incentivize using both in parts of the rest of the system. At this point, I realize I probably sound like I'm campaigning to reinvent my previous RPG. I haven't decided what "the next next project" is going to be, so anything is still possible, at this point.

...

Next post is due on Nov. 30th, when (if all goes well) we should be unveiling the Spellbinder and Warlord classes -- so check back then!