I must create a system, or be enslaved by another man's. I will not reason and compare: my business is to create.

- William Blake

Thursday, January 11, 2024

Single attack/damage roll

Last year, I've read a Reddit user (Kubular) talking about a single attack/damage roll, and ever since I cannot stop thinking about this.

Just roll 1d20, add your attack bonus, a "weapon rating" (WR) and subtract AC: this is the total damage (minimum 0). 

(I'm assuming ascending AC here; if you're using THAC0, add AC and subtract THAC0, etc.)

Example: if you roll 15, your attack bonus is +4, and your WR is +3, your total is 21. Against AC 17, this means 4 points of damage. But against AC 10, you deal 11 damage!

This has innumerable benefits

- One fewer roll, for starters. Faster combat.

- It prevents the disappointment of "I rolled a 19 in my attack - perfect! Roll damage... 1 point... sigh...".

- Armor becomes immediately vital. When unarmored, being hit by a dagger (held by a capable fighter) is DEADLY even at mid-levels.

- At the same time, weapon choice becomes more important against armored foes, beyond a simple +1 damage.

- Bigger weapons are better, but even MORE relevant against armored targets - going back to CHAINMAIL days.

- Fighters become more deadly as they progress WITHOUT the need of multi-attacks. Conan can now kill an unarmored sorcerer with a chair, or with a single blow of his sword.

- Lines up perfectly to the AD&D advice (IIRC) that excess bonuses after you "always hit" go to damage (e.g., if you had +15 to hit against AC 11, you immediately add +4 to damage).

- It is also perfect for B/X, where a fighter will rarely have an attack bonus much greater than +10, so things never get out of hand.

- This lines up well with the idea that monster damage raises on average one point per HD, something Gygax suggested and I have discussed in this blog before. 

- It can also reduce monster stats; their damage is derived from their attack bonus/HD, no need to list damage for most monster attacks (and two attacks could just get -2 each, thus reducing to-hit AND damage and sometimes creating an interesting choice - attack more often if your opponent has weak armor, etc.).

- Now the bonus to attack/damage is a single number. Str gives you +1 to attack/damage, and a magic weapon might give you an additional +2 attack/damage. B/X already does this; now, weapon damage follows the same pattern.

- There is always a small chance of near failure. Even a lowly goblin can survive a blow from a +5 sword if the attacker rolls badly.

Source: stupidcircus on Facebook.

Calculating damage is a bit tricky. 

Basically, if you hit on a 11+, you have 50% chance to hit, and your average damage when you do is 4.5 (the average of all possibilities, from 0 damage on a natural 11 to 9 on a natural 20) - so average DPR is 2.25 (see table below).

If you ALWAYS hit, average damage AND DPR is 9.5. 

If you need a nat 20 to hit, since the difference is ZERO, you can cause no damage - of course, you could rule that the MINIMUM damage is 1, so the DPR would be 0.02.

As you can see, average damage is nothing absurd - even if maximum damage varies wildly. 

DPR is lowered against heavy armor, and augmented against  unarmored foes.

For example, a d4 dagger usually has a DPR of 1.25 if you need to roll 11+, but if you use this system and consider the dagger a +1 weapon, the DPR goes to 2.75 (since you hit on a 10+).


Roll needed

1

2

3

4

5

Dmg

9.5

9

8.5

8

7.5

DPR

9.5

8.55

7.65

6.8

6

Roll needed

6

7

8

9

10

Dmg

7

6.5

6

5.5

5

DPR

5.25

4.55

3.9

3.3

2.75

Roll needed

11

12

13

14

15

Dmg

4.5

4

3.5

3

2.5

DPR

2.25

1.8

1.4

1.05

0.75

Roll needed

16

17

18

19

20

Dmg

2

1.5

1

0.5

0

DPR

0.5

0.3

0.15

0.05

0



There are also potential shortcomings

- Punches could become too deadly, even if you rate them as -4.
- Likewise, unarmored targets are very frail. Barbarians, monks, or maybe EVERYONE might need a small AC boost at higher levels.

And some ways to spice/fix things up.

- Maybe weapons are +1/+2/+3/+4, with swords giving you +1 damage and maces giving you +1 attack and -2 damage (so they are better against armor), etc.
- Maybe there is a soft limit to damage (e.g., 5/10/15/20), so strong fighters benefit more from bigger weapons.
- Instead of assigning bonuses to weapons, just roll a d4/d6/d8 etc. So, d20+d4+attack bonus for a dagger, and so on, making things even more swingy and deadly. Maybe use unarmored AC 12 to balance things out.

Would I use this in my B/X games? I'm not sure. 

I think it would be a great fit for a "Song of Ice and Fire" type of campaign, or maybe some gritty Sword & Sorcery. 

I'm not sure my players would buy the idea for traditional D&D games - they are just too used to rolling damage.

11 comments:

  1. I tinkered with something very similar a while back, and couldn't quite make it work to my satisfaction. One thing that just occurred to me would be to use 2d10 rather than d20, creating a curve instead of straight linear result, pulling the roll away from the extremes and the damage more toward the average, with decreasing odds of getting the really big hits. I haven't crunched the numbers, and it might be a bridge too far for those who are married to the d20, but it seems at least mathematically plausible.

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    1. I think it could be an interesting alternative, but you might have to lower some of the highest ACs or someone in plate would be almost impervious.

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  2. Great topic, a recurring one for me, I'd say. First let me point to:

    https://www.necropraxis.com/2013/09/16/degree-of-success-as-damage/

    as this was already being discussed the freaking amount of 11 years ago.

    I like your final idea of d20 + weapon damage die + Attack Bonus vs AC. Let me propose you another:

    Your attack bonus takes the shape of a die (from d6 to d12, fighters starting maybe at d8) + every weapon has a die also (d6 fist, d8 dagger, d10 swords and d12 two handed). This approach would require all ACs to downgrade a bit to work but is very visual and does away with a triple sum (d20, weapon and attack bonus)

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    1. Yes, it is not necessarily a new idea, but something that called my attention.

      Dx+dx could work too!

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  3. Thank you for the post Eric - always enjoy seeing how you wrangle different mechanics. Jack and WW's ideas using 2 dice for a triangular distribution would be fun to muck about with (getting close to Maze Rats and Tunnel Goons), but I will focus on the original d20 hit-and-damage roll for now. Firstly, I'm going to remove DEX modifying AC in all of the following. Secondly, unlike Necropraxis, I'm happy to just treat an attack equal to AC as a miss. I'm likewise one of those slobs who is happy to waive the one pip (5%) difference between B/X and AD&D AC values!

    I note that assuming no attack bonus (ie first level and ignoring any 'weapon factor'/WF for now) the damage per hit against unarmored (AAC 10) is 1-10, leather (AAC 12) is 1-8, chain (AAC 14) is 1-6, and plate (AAC 16) is 1-4. This perspective has pleasing 'mechanical aesthetics' and demonstrates intuitively that the rule does not break the game, and actually stays within the expected bounds for damage on hit extremely well! You get attacks ranging from equivalent of d4 to d10 damage on hit, but now varying based on defender's armour rather than attacker's weapon.

    It also reveals why adding in an additional WF can so quickly inflate the damage per hit or round against traditional AC values: if you say give daggers +1 up to two-handed swords +4 WF, that is equivalent to d11 to d14 damage dice (even ignoring the increased chance to hit). I see a few appealling configurations:

    1. OD&D-style: Run this 'neat' without WF, use original 10-17 AAC, and pair with attack bonus equal to HD with variable rate of HD gain per class. Keeps arithmetic (integer size and number of computations) down, addresses the slowing down of high level combat, and elegantly gives Fighters a sense of combat mastery. Just a +1 attack from two-handed weapons (analogous to the +1 AC from shield) should be enough if desired.

    2. Modern D&D-style: Include WF (eg. +2/d4 dagger up to +6/d12 two-handed sword), use modern 10-20 AAC, higher starting HP (max of d6-d12 HD at first level or else 3d6 CON score seems about right), and keep 1 HD/level. More arithmetic (though static WF can just be incorporated into your attack bonus on sheet) but better preserves weapon differentiation.

    3. AD&D-style: Combine this with a simplified Weapons vs Armour table such as Robert's (I presume?): Certainly the highest yield (ie impact for effort) version of WvsA I have seen yet!

    X. Troika!-style: You can THEN add in to any of these a contested pêle-mêle roll - each side rolls their attack, highest wins and only they inflict damage. If you determine damage as your Attack roll minus (higher of opponent's AC or Attack) then you even get a fairly elegant parrying mechanic with escalating damage mitigation by level. You might be able to drop rising HP totals entirely, and options 3+X gets you a rather nice 'gritty' combat system without much fiddling, I reckon.

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    1. For some reason the link to the simplified Weapon vs Armour table on Strange Magic got gobbled up: strangemagic.robertsongames.com/2011/09/weapon-vs-armor-tables-for-bx-d.html

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    2. Thank you for the comment!

      I don't mind the 5% difference either, but I'd probably say that an attack does a minimum of 1 damage just because my players are used to it.

      I do realized give weapon bonuses would make the system too deadly; and I really like your parrying suggestion, since it would create another layer against crazy amounts of damage (I might even call it a "defense" or "dodge" bonus to allow fighters to defend against arrows too!).

      There is an entire new system to be explored there: acrobatic dodging (something I tried to incorporated in the Dark Fantasy Basic feat), parrying weapons, fighting multiple opponents (limiting the number of parries or giving them a penalty, etc.).

      The "Weapon vs Armor Tables for B/X D&D" is very nice too. I've been trying to come up with something similar for a while now; the goal is having something as interesting as AD&D but as simple as B/X.

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  4. It's been a while since i have commented on this blog (life has been super busy). I am glad to see you are still going strong! This is a bit of a ramble, but it lets me get all my thoughts out of my head in a (hopefully) coherent fashion.

    This ties more into some broader musings of mine but could one collapse this 'one roll' mechanic into the general resolution mechanics for weapons and skills?

    So you have a general probability curve (the 1d20 or 2d10) and then you modify the curve with tool bonuses (which would be weapons) and skill level (be that proficiency dice, a bonus, and other attributes) and then you have a set DC. In this discussion between weapons and armour types, perhaps a general 'circumstance' bonus and an 'aid' bonus from another player can be considered so that you could check off the following:

    2d10 - general probability (always)
    skill - if you are trained or expert (always on)
    raw ability - flat bonus (always on)

    Tools - quality of tool for the job applies to anything the tool is used for correctly (You are deliberately applying)

    Circumstance - Additional things that help (think environment, weapon vs. armour bonus) - Up to the GM

    Tactical - Think aid from an ally, flanking, etc. Take the highest bonus.

    So this should be fairly easy to track (in my opinion) and since one isn't doing additional steps in combat, and this is the general system, i think familiarity will come rather quickly.

    I have mentioned before that I am partial to the idea of a 2d10 curve with a proficiency die that then has an 'expert' tier that maximizes the die so that the trained and the expert character have the same range of outcomes, but completely different 'experience' of that range.

    In combat, HP represents your ability to 'readjust' to having your defenses breached (stamina/reserves) and a blow bringing you to 0 is the blow that gets through.

    Skills could have a reasonable degrees of success tied to them as well this way (imo) because with one roll to consider, you can 'add back' some complexity that make intuitive sense for extra flavor (thinking of failing a DC by 5 means X bad thing, beating by 5 is X good thing).

    A short note to end the ramble: I know I am talking about throwing a bunch of dice for the resolution, but I do think that an attack matrix resolves a lot of that complication with able to check your roll vs. success/failure pretty quickly if mental math is too much.

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    1. Hi Sean! Great to have you back!

      Using 2d10 works great for many systems - I've tried it myself. For D&D, it would require some fine-tuning for combat, but I would be pretty good for skills without any other modifications, I think.

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    2. I would think that fr combat if it's not as 'close' one would like, HP can be adjusted to make up the difference. It being the secondary defense of a creature to 'recorrect' works well for that idea.

      (Amusingly, a similar idea of a lock providing a similar issue to a rogue makes me picture a flea shoving away the lock pick as it comes close)

      Unfortunately the tables I am at are likely not so up for just trying different systems (for one we are all online so it's not just chucking dice and paper), or else I would play around with it more in practice instead of just musings and the rare couple of notes on some scrap paper to sketch them out.

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    3. Yes, I see what you mean... my friends are not that interested in house rules either, and prefer to run he same systems over and over.

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