Splitting up Hit Dice: Mass and Fighting Ability

Here’s a tough mathematical problem I’m wrestling with when it comes to static dodge/parry values.

Assume a 1st level fighter with sword and shield (AC 1, 5hp, attack throw 10+) is attacking a 1st level fighter, similarly equipped. The fighter will hit his foe 50% of the time. On a successful hit, he will deal 1d6+1 damage, with 50% of the blows being enough to kill (and 2 hits will almost certainly kill). It will therefore take 4 rounds, on average, for one fighter to slay the other.

Now assume that the foe is a 2nd level fighter with 10hp. Now it will take, on average, 8 rounds for the fighter to slay his foe.

Now assume that the foe is a 3rd level fighter with 15hp. Now it take, on average, 12 rounds for the fighter to slay his foe.

Note that the increase from level 1 to level 2 is a doubling of survivability, but from level 2 to level 3 is only a 50% increase. From level 3 to 4 is only a 25% increase, etc.

Assume that we want to switch to a system where HP are static and improved odds of survival are based on an increase parry/dodge value (“defense class”).

In order to simulate this, we’d have to give the 2nd level fighter a defense bonus that halves his chance of being hit - roughly along the lines of a +5 bonus, so that it goes from 11+ to 16+. Then from level 2 to level 3 would be a further increase to halve it again, so from 16+ to 18+.

BUT the mathematics are difficult because when armor changes the mathematics change. If the same fighters are in plate (AC6), they need 16+ to hit each other. That means that to double survivability a parry bonus of +2 is all that’s needed.

So to offer our 2nd level fighter the equivalent of “another hit die” what should his increase in defense bonus be…+5 or +2?

Very tricky…

Ah. OK. Yea, I don’t see that necessarily working out without a complex dance between upper AC limits and attack throws, perhaps determined by the comparative hit die of the combatants, else combatants correctly armored or leveled will be unhittable but on a natural 20.

That’s still doubling up on armor as avoidance rather than ablation, however. You’d think there’d be a system somewhere that’s figured this one out.

Randomly, Mutants & Masterminds 3E (SRD available here: http://www.d20herosrd.com/) abstracts Hit Points completely away. An attack throw is made much like normal d20 (Fighting is a ability score here, much like the old FASERIP system) The roll must beat the target’s Dodge or Parry, depending on the attack type/capabilities of the defender.

If the hit is successful, the target must make a ‘Toughness’ saving throw against 15 + the rank of the Damage effect - a sword is Damage 3, so the save is DC 18.

Toughness is modified by your Stamina(Constitution) and armor. Plate is +5 to your Toughness, for example.

M&M isn’t level-based, but I could see wanting to increase Toughness based on level.

Failed Toughness saves (they fail by degrees) start stacking on each other. Eventually you’re just killing yourself with penalties to that save - Back when it first came out there was a bit of concern over a ‘Toughness Death Spiral’, since then I’m not sure if that concern has lessened, but there were several ways to ameliorate that a bit, one of which I used (http://crowbarandbrick.blogspot.com/2012/11/true20mm-static-toughness-roll-damage.html)

The M&M damage system is great! I actually borrowed it for an ACKS-Cyberpunk rules hack I was working on. But I encountered some outrage from players who felt that the game no longer was “D&Dish” without the hit points.

Interestingly, from the point of view of realism, damage saves are much more reflective of how injuries impact the human body. The wound is either slight, and irrelevant; disabling; or mortal. The historical records of duels are full of tales of men who took 5-20 wounds and lived, and then slew their enemies with 1 wound. Since the enemy was often a great duelist himself it’s hard to argue this was “hit points”.

The same goes for gunfights, which is why that seems especially appropriate for Cyberpunk games. Sometimes, some people take 10 or more gunshot wounds without apparent effect, some people are killed or disabled by 1…

Of course, in both cases there’s the chance that one of the wounds that didn’t incapacitate you is bad enough to kill you minutes, hours, or days after the fight.

This isn’t D&D by any means, and I’m not sure I’ll be able to win my D&D-playing friends to play this, but otherwise I LOVE this. Much simpler than the above solution! And makes combat interesting to boot.

What it needs is very rigorous playtest, as I fear it might have unintended consequences.

One could make the long-term consequences bit a part of the healing subsystem; when you go to heal off a significant wound level (I’m thinking Wounded or worse in True20 terminology), you have a small chance of instead dying, developing an infection, or some other complication.

I liked True20’s damage system (basically the same as M&M’s) on the occasions when we played it, and my groups mostly did not object except for the occasional critical failure resulting in sudden PC death. Might have to go cook up an ACKS hack (hACKS?) with it now. Seems quite appropriate for cyberpunk, and I’ve been meaning to build a sort of ACKS-40k sci-fi variant, for which this seems a very reasonable damage system. I’m curious - did you integrate these mechanics into the Death and Dismemberment table rolls?

Three more notes:

  1. The main thing which worries me about armour-as-damage-reduction rules is that it might cause grind, as fights between armoured oppponents do relatively little damage. How do you intend to solve this?

  2. How do ranged attacks work, such as missiles and especially bullets, can they be dodged?

  3. I wonder how lethal adventuring play would be. As lethal as vanilla ACKS? More lethal? Less?

  1. Armor as damage reduction can make games quite a grind, if weapon damage is close to damage reduction. If damage greatly exceeds damage reduction then it is moot.

One problem with armor as damage reduction is that historically, armor worked. That is to say, attacks which hit armor were misses; and successful attacks were those that found gaps in the armor, not those that got through the armor.

From Sumer to Ancient Rome has fascinating information on this. A typical melee weapon would generate 70-100 joules of KE. To penetrate 2mm of bronze on leather took in excess of 120+ joules. “Oh, but the bludgeon force will still kill you”. No, in fact, a 110-joule blow from a mace gets distributed by the armor, such that it is reduced to about a 15-joule blow.

If one wanted to be realistic, you would need a system where:

  1. armor serves as a divisor (e.g. 1/2, 1/3/, 1/4), rounding down so some blows deal no damage, for attacks hacking through armor

  2. armor serves as a penalty to hit for attackers who are avoiding armor

  3. Yes, I think so.

  4. Don’t know… I think it would be very easy to screw up the game!

Oh, that’s interesting - that does shift my view on avoidance vs. ablation. I’d figured there was some distribution, no idea how much.

Google Books has the ToC and an index of tables/illustrations…

Table 4.7: Wound Lethality in the Iliad by Area of Body

That…that might be too much for me :slight_smile: May have to see if I can get it via the library - even the e-book version is college textbook priced.

Given two plate-mailed combatants of equal capability having at each other, you’d think just standing there hacking away just ringing blows off their armor would fatigue one sooner than the other. That’s not exciting DND combat though.

Earlier in the thread, many of you brought up Conan D20 and its use of “Defensive Bonus” and “Armor as Damage Resistance”. This evening I worked through scores of different battle combinations to compare different combatants under different rule mechanics to see if I could find a set of rules that would yield approximately the same outcomes as Armor as AC.

Here are those mechanics.

  1. All combatants possess a Defensive Bonus of (10-Base Attack Throw)/2, rounded down. Defensive Bonus is increased by DEX modifier, Bladedancer’s Graceful Fighting, Swashbuckling proficiency, magical items and spells “of protection”, “displacement” or “shimmering”, and spells that improve AC through luck, speed, or divine favor. Because highly dexterous targets are harder to hit than sluggish ones, a target’s Defensive Bonus is added to the attack throw value necessary to hit it.

  2. When a target is struck, it reduces the damage dealt by its Armor Class. AC is improved by armor, shields, magical adjustments to armor and shields, Weapon & Shield proficiency, magical items “of armor”, and spells that create magical armor or shields or render the subject “invulnerable”. Any attack deals at least 1 point of damage. An attack dealing dealing 10 or more points of damage before armor deals a minimum of 2 points of damage after armor. An attack dealing 20 or more points of damage before armor deals a minimum of 3 points of damage after armor, and so on.

  3. All combatants possess the capability of scoring critical hits. The likelihood of scoring a critical hit is based on the attacker’s modified attack throw (including target’s defensive bonus):
    16+ : No critical hit possible
    11-15: Natural 20
    6-10: Natural 19-20
    1-5: Natural 18-20
    -5-0: Natural 17-20
    -6- -10: Natural 16-20
    etc.
    On a critical hit, the target suffers maximum possible damage, ignoring armor.

How do these rules impact the length of combat?
At levels 1-4, fights are approximately the same in length. The defensive gains a slight edge, making them about 8% longer.
At levels 5+, fights are about 30% longer. The increase in Defense Bonus from leveling up, combined with the variety of magical protections available, does make things a bit longer.

THEREFORE (OPTIONAL)
4. Increase damage die of all weapons by one step, such that small weapons deal 1d6 damage, medium weapons deal 1d8 damage, medium weapons wielded two-handed deal 1d10 damage, and large weapons deal 1d12 damage.

INTERESTING SIDE EFFECTS
Under traditional ACKS rules, a 9th level fighter (plate +2, shield +2, sword +2, weapon & shield proficiency) will kill a fully-buffed 9th bladedancer (2 swords +2, leather +2, weapon finesse, swashbuckling, shimmer, swift sword, striking) in 10 rounds, while the 9th level bladedancer will kill the fighter in 14 rounds, meaning the fighter will tend to win. Under the rules presented here, the bladedancer will kill the fighter in 11 rounds, while the fighter will kill the bladedancer in 13 rounds, meaning the bladedancer will tend to win.

At first I thought this was anomalous, because the bladedancer’s d6+2 swords can hardly penetrate the fighter’s armor, even with a spell of striking. But the impact of criticals is disproportionately felt by high AC characters, and two weapon fighters, or other characters with great attack throws, fighting low-DB opponents, score crits quite frequently.

OTHER NOTES
Weapon Focus proficiency should apply to any critical hits, and allow the character to deal an additional roll of damage on top of the max damage.

Interesting!

Is having a 9th-level BD be able to kill a 9th-level Fighter on average a desirable outcome?

Hm.

I wonder how the simulation changes if the shield’s AC bonus is given over to the Defensive Bonus rather than Armor Class, under the (half-baked) theory that putting a wall of metal or wood betwixt you and a weapon is just as good as dodging?

Given that it’s a best-case situation for the bladedancer (she has all of her buffs up and the fighter has no buffs at all), I think it’s fine.

If the bladedancer doesn’t have Shimmer, Striking, and Swift Sword, it’s a wipe-out.

I wrestled with that. I think if one looks only at man-to-man combat that makes sense. But when you add giants and ogres and dragons to the mix, it becomes apparent that the shield can’t really block 100% of such an attack.

Hm. That would be true, excepting Steve Rogers. I could see some additional bits to fix that alongside/related to the minimum damage rules you had above but I doubt the extra complexity would be worth it.

I don’t think I was entirely clear. I’ve played with these rules, and I am familiar with what they do. My question is: why is that of value to you? Saying, for example, that they make sense of the progression of weapons as armour got heavier, or that they force/encourage players to choose different weapons is fine, but doesn’t tell me why you see value in this where I see none (or so little it isn’t worth the effort). Having players juggle weapons because of this just becomes a mini-game in and of itself, and I see no more value in it than I do in clever grid tricks in 3.x or 4E, not to mention that it gets particularly strange with monster ACs. As far as a realism angle, the rest of the system is so far from that that the introduction of Weapon vs. AC isn’t nearly enough to scratch that itch for me.

Also, just to be crystal clear, I am not trying to slag anyone for liking these rules. I want to understand what the underlying motivation for adopting them is. Verisimilitude or realism? A style of “tactics” that requires the right weapon for the right job? Something else?

In my particular case I just like verisimilitude. Thomas Weigel has often said that ACKS reminds him of GURPS, in that I take a very reality- and physics-based approach to my designs. So I sometimes wrestle with the fact that the combat is based on such a complete abstraction. Which is not to say that ACKS combat isn’t fun – in fact, pound for pound, I reckon it has the best example of D&D-style combat, and in particular, the best balance between fighting and magery – but that doesn’t mean I don’t occasionally grimace at the abstract nature of it all.

Also, I don’t think that AD&D with Weapons v. Armor rules was a fun or playable system. But I do acknowledge that the system made much less “sense” in terms of world-coherence when those were removed.

Ah, okay. Fair enough. I agree with you, generally - that’s why I tried to adopt those rules several times myself. I think I’ve finally (mostly*) given up on “realism” in D&D; the system just isn’t built for it, but it’s plenty fun and playable.

*I say “mostly” because part of the attraction of ACKS is its somewhat simulationist bent which extrapolates the rules to their logical, in-game conclusion. In spite of that, it still maintains the best of the playable core of the game.