10
Jun
11

experimental combat system

Quick post because I have to get to work.

Several months ago I was wondering about how to separate deflection-type protection (shields, dexterity) from soak-type protection (armor).

In cases of uncertainty, the baseline here is the Moldvay/Mentzer Basic D&D combat system.

  1. Typical combat sequence is unaltered. Variable weapon damage is used.
  2. Attack rolls are made as usual in D&D: 1d20 + (class attack bonus/THAC0 stuff) + (ability mod) + (magic mod) + (circumstance)
  3. Ascending Deflection Class = 11 + (Dex mod) + (shield & shield magic mods) + (circumstance). Note: no actual “armor” in this calculation.
  4. If the attack roll equals or exceeds your deflection, guess what – you’re hit.
  5. If hit, Armor decreases the size of the damage dice: 1d10 > 1d8 > 1d6 > 1d4 > 2 > 1. Any hit does at least 1 point of damage, regardless.
  6. Multiple dice-types (3dX for example) shed the extra dice first, and once they hit 1dX then degrade to the lower dice type.  So 2d6 > 1d6 > 1d4.
  7. Light armor reduces the damage die type by one step, medium armor by two steps, and heavy armor by three steps.
  8. Damage is then rolled “normally” – the modifed die type + (ability mod) + (magic mod) + (circumstance)
  9. Magical armor lightens your Encumbrance Category, e.g., a heavily laden warrior in Plate +3 moves as if totally unencumbered.
  10. Monsters don’t have to be changed, but they could be depending on your ambition. An attack doing 1d3 damage reduces to 2 points, not 1.

Thus: Arnold Littleworth, under this system, has a Bathrobe of AC 4, which is equal to Chain + Shield. His Deflection class is 11 (base) -1 (poor Dexterity) +1 (equivalent to shield) = 11.

If, solely for the sake of science, Martin le Black attacked Arnold with his +2 sword Bazilien, his attack roll would be executed normally, hoping for a roll equal or better than 11. Because Arnold’s Bathrobe is equivalent to Chain armor, the damage from Bazilien would be 1d4 (starting from 1d8 and reducing two steps) +1 (strength) +2 (magic).

Action Normal B/X D&D Experimental System
Martin hits Arnold … 60% of the time 80% of the time
On average Martin inflicts 7.5 damage 5.5 damage
Expected damage per round 4.5 damage 4.4 damage

Note a couple of effects from this experimental system:

  • Armor reduces damage, it doesn’t keep you from getting hit in the first place.
  • Magic-Users and Clerics can make “touch attacks” to overcome Deflection Class much easier than AC
  • Characters are hit more often for less damage. Armor is approximately twice as useful as before, which helps Level 1 wimp-o’s.
  • Damage reduction is neither fixed nor does it require an extra roll, i.e., it’s unpredictable without slowing play
  • Against a guy with heavy armor, a dagger +1 does the same damage as a normal sword (more, on average, since it hits more often): magic is cool
  • Heavily armored knights are slow and easy to hit, but very difficult to wound without magic.
  • The special thing about Frodo’s undershirt is that it was extremely lightweight and easily concealed – like not wearing armor at all.
  • Maybe someone other than me will enjoy the strategic effects of Encumbrance… oh who am I kidding

Just to see what it would look like, here is the comparison for a duel between Martin le Black and Hanna Darrowkin, using their stats as of 1/9/2011:

Action Normal B/X D&D Experimental System
Martin hits Hanna … 25% of the time 55% of the time
On average Martin inflicts 7.5 damage 5 damage
Expected damage per round 1.875 damage 2.75 damage
Action Normal B/X D&D Experimental System
Hanna hits Martin … 30% of the time 60% of the time
On average Hanna inflicts 3.5 damage 1 damage
Expected damage per round 1.05 damage 0.6 damage

What’s happening here is that Hanna, physically weaker, is using what amounts to an ordinary sword to attack a stronger foe armed with a larger, more heavily enchanted blade. Both duelists are very heavily armored, but over time, Martin’s superior strength and magic can punch through the Halfling Hero’s defenses.

I still need to figure out:

  • What to do against touch-style attacks, like Wights and Vampires?  They become a lot deadlier under this system.
  • Do Hit Dice change? I’m thinking that combat between heavily armored dudes would take too long at standard Hit-Dice values.
  • Maybe each type of armor stays vulnerable to a particular type of damage (Piercing, Slashing, Bludgeon), if people think armor otherwise is too good.

9 Responses to “experimental combat system”


  1. 1 M
    June 10, 2011 at 1:50 pm

    Very, very cool. I appreciate the tactical/strategic choice re Encumberance as well; as long as it is a simplified encumberance system such as the Stone based system. It reminds me in a way of Dragon Warrios, which is a good thing.

    I like the idea of touch attacks being easier in this system. You may or may not want to let magical armor add some added deflection versus such attacks OR reduce the effect OR better yet act as a bonus to saves vs. level drain. Itmakes that shiny paladin magical plate all the more iconic. :)

    The reason I like the being easier to hit aspect is it supports with mecahnics the genre image of the unarmored adventurer, barbarian, etc. , that lives by just not being hit. Otherwise there is no in-game reason under old D&D to not armor yourself from head-to-toe in plate if the rules allow.

    I have used a system similar to this for about 20 years where armor absorbs damage but decreases your initiative. As hits are resolved in order this can make a difference. Against humans and lower damage dealers armor can be a very good bet unless you want to try to finish them first. Against monsters such as giants, dragons, other high damage dealers or area effect damage dealers, armor helps but it won’t stop a world of hurt. In these cases getting to act first may be a better bet. In play over the years most players opt for medium armor choices with little initiative penalty but their isalways one who goes all out tank. A useful combination allowing the party to deal with a range of threats effectively.

  2. June 10, 2011 at 2:23 pm

    Interesting. A couple of thoughts: conceptually, a lot of the protection of armor was deflection, rather than soak, and it was constantly being refined to make deflection from vital areas more likely. I think that’s particularly true when you compare armor against the weapons that were designed to work against it. E.g., as I understand it, plate was fully proof against the sharpened edge of a sword…so they stopped sharpening the edges of swords and started concentrating on being able to ram the pointy bit in (estocs and the like)… so armorers responded with smoother, more curved armor, particularly where it counted around the throat and arm pits, and so on. I’m not sure how or if you want to account for that.. It might add too much complexity, but I’d almost like to see different ratings against Slashing, Piercing, and Blunt.

    As far as heavy armor being too good and dragging out fights too long, I’d suggest using exploding dice (every time you roll the highest possible, you reroll and add), representing finding a chink in the armor. That would mean that weapons that had been reduced by soak to d1 would be hopeless, but even a weapon that had some chance of penetrating (say a d4) would be able to get lucky… a couple 4s in a row would be like getting the point in the eye-hole. I use that mechanic in my D&D house rules, and it works pretty well for letting them feel pretty confident in their armor most of the time, but still wary of a lucky blow.

  3. June 10, 2011 at 2:33 pm

    I’m guessing it’s not a problem in your experience of play, but the extra step of “okay, which damage die do I need to be rolling?” would be very unpopular in my group, and lead to some rather aggravating slowdown.

    Also, assuming I have this progression right, it would bother me to see a 2d6 damage weapon drop to 1d4 (per your explanation) even as a 1d8 damage weapon also dropped to 1d4 (1d8 -> 1d6 -> 1d4). Does Moldvay/Mentzer D&D include Str bonuses to damage? (I am so not an OSR guy.)

    Out of curiosity, what are your objections to giving armor a fixed die for damage mitigation, with the note that no hit can be reduced below 1 point of damage? (Maybe d4/d6/d8 for light/medium/heavy?) Maybe I’m not understanding your plan correctly, but it looks like your system makes Leather +1 identical to Leather +3? (This is based on the assumption that the same amount of magic can be applied to all grades of armor.)

  4. June 10, 2011 at 2:52 pm

    Metamorphosis Alpha 1E has different damage dice for each weapon when attacking humanoids or creatures or unmutated humans, which I found both conceptually odd (‘creatures’ seems to me to cover such a lot of ground compared to humanoids vs. pure humans) and difficult in play. AD&D’s different dice vs. S-M or L makes more sense and is easier to remember to apply.

    I think it was Alexander Macris of the Escapist (and its Check for Traps column) told me that historical evidence of battlefield wounds and the like indicates that almost no one was ever killed by wounds on places that were armored; whatever weapons were contemporary relied on being able to get into unarmored places. So the idea that armor makes you harder to hit by denying an ever-wider range of easier targets seems to hold some validity, as SCA participants might have known firsthand.

  5. 5 Naked Sam
    June 10, 2011 at 5:33 pm

    I want to point out Hanna now has a +3 Short Sword and Martin is the size of a halfling and cannot weild Bazilien.

  6. 6 Lord Bodacious
    June 10, 2011 at 6:43 pm

    I think it’s worth noting that even with Martin’s small size and wimply sword he would still totally kick Hanna’s butt.

  7. 7 Naked Sam
    June 10, 2011 at 7:18 pm

    Doubtful! Martin is a poopy-head.

  8. June 11, 2011 at 9:12 am

    this could be semplified with different damage vs different armor

    e.g. a longsword instead of 1d8 would do 1d8/1d6/1d4/1d3 damage (it could be easy to get carried away)

    still I think the problem is still “what we want hp to be?”

  9. 9 Bargle
    June 11, 2011 at 3:47 pm

    Why not assume armor is what makes the difference between a Mu d4 hp and the fighters d8?

    Assume chain armor gives you d6 plate d8 leather/nothing d4.


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