April 18, 2011

Armor as Hit Modifier

I am about to commit an act of heresy.  I’m going to say that it actually does make sense for armor to be a to-hit modifier as it is in D&D.  Say what? Dariel are you falling for that b-s- again?!

Well, consider what it takes to go through armor as opposed to going around it.  I’m not saying the idea of armor as damage reduction is bad, but rather that the choice need not be exclusive. Most of the time, muscle-powered weapons will not cause significant injury unless they strike an unarmored part of the body. It takes a really heavy weapon, the strength to wield it properly, or better yet an energy source stronger than muscle –e.g. gunpowder – to truly pierce armor.

How can we model this?  We have to regard armor now in terms of two properties, coverage and material strength.

Coverage refers to the amount of body protected by the armor, with a 15th century style full plate panoply including helm, arm and leg defenses as the ideal, down to single-piece partial armors like having only a Roman gladiator’s manica.  This means each piece of armor will matter now. Helmets will add a bonus, as will shields, greaves, vambraces, pauldrons, gauntlets, etc. etc.

Let’s then consider Material Strength. This is the difficulty of piercing or cutting through the material the armor is made of, and takes account of both the material – leather, bronze, iron, etc. – and the construction technique used to build the armor.

Compound AC
I’m thinking, for simplicity, to give AC as a compound of Coverage and Material Strength.  The base AC is from Coverage, then we’ll tack on bonuses if the material is good (assuming the base material is pretty soft, something like quilted linen or tanned leather). 

You’ll have pretty decent chances to hit a barbarian in a leather vest and nothing else, but good luck fighting that antipaladin in full panoply of adamantium plate!

Changed Damage Dice
Another idea is to keep AC based entirely on Coverage, but change weapon damage dice based on the Material Strength of the armor.  The premise is that if a hit did go through the armor, the armor would reduce the damage; or if it did bypass the armor’s coverage, the hit still went somewhere less vital.

So you could for example posit that damage for any weapon is 1d12 vs no armor at all, 1d10 for light armor, 1d8 for medium armor, 1d6 for heavy armor, and 1d4 for very heavy/very hard armor.

For critical hits, assume that the hit was made to an unprotected spot, so use the highest damage die.

Armor and Dexterity
What about the DEX bonus? I’d say it applies only if the character is wearing armor of a certain weight or less.  Perhaps base it on character Strength. 

If your AC from armor alone exceeds a certain proportion of your STR, no more DEX bonus.

This means that the light-armed swashbuckler is as valid a concept in combat as a tanklike knight, but they will have to fight quite differently.

With each piece of armor now important, you can play with tactics aimed at reducing your opponent’s armor coverage.  Break or otherwise take away his shield.  Get him to take off his helm.

You can also choose between defensive strategies.  Will you risk going in with less armor, relying on your high Dexterity bonuses for protection but chancing more damage per hit, or will you trade a higher chance of being hit for a lower damage die? 


  1. That varaible weapon damage vs armor is a really interesting idea Dariel.

    BTW I'm thrilled to have discovered your Blog. My wife is from Davao so its great to hear from a Pinoy game designer and photographer too.

  2. Thanks! Guess what, my wife is from Davao too. :)

    BTW I saw on your profile that you're an archaeologist. I'm designing a pulp adventure game right now, mind if I ask you some questions about the field if I need info?

  3. Cool. I'd be happy to answer any questions or discuss any ideas you'd like to bounce off me. Archaeology varies a bit from country to country. In some countries (Britain) it is treated as a seperate discipline, but here in the US about 90% of archaeologists are anthropologists who have specialized in the anthropology of past cultures. The other 10% are "Classical" archeologists who are primarily interested in the art and artifacts of the Mediteranean (Greece, Rome, Egypt, Palestine). So there are some different goals to be aware of.

    Anyway you can email Boggswood@Gmail.com

    April 27, 2011 6:15 PM

  4. In D&D most muscle powered weapons do not cause significant damage to armor: your armor isn't considered broken at the end of a fight. In the case of a piercing or slashing weapon the opposed attack roll models finding a chink in the opponent's armor in most cases, or else on piercing a stress point (such as where the armor is curved to fit the body). In the case of a bludgeoning weapon it's modeling the idea of transfer of energy. So, even though the weapon hit your armor, it has hit hard enough to make the armor buckle and dent (for metal armor, if you're wearing leather it's because the weapon hit with enough force to hurt through your armor). Bronze is so soft that a good weapon swing would similarly hurt even through the armor, although I could see bronze armor giving a damage reduction 2/bludgeoning or something. This is of course why most weapons in the ancient world were piercing or slashing. As to the assertion that "most muscle powered weapons couldn't go through armor" I think you're forgetting that medieval straight swords were designed to be swung downwards. Thus you benefited from not only your own strength but also from gravity. Most knights would have had trouble cutting another knight's head off, but they would have had very little trouble cutting another knight diagonally from shoulder to hip, or from head to groin. Assuming they could actually get above their opponent and in a position to do this(usually they accomplished this by unhorsing him, then dismounting before he could get up). This is why dexterity modifies armor class: because you can move to deny your opponent the benefit of gravity and thus reduce the chance that he'll cut through your armor. In the real world scimitars and axes are only really good against chainmail, they pretty much just bounce off plate but for game mechanics having a sword that only works on chainmail and leather is too complicated.


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