Sunday, April 1, 2012

A to Z Challenge: Armor & Armor Class

A is for Armor and in D&D it is most well known as Armor Class or AC for short.  In typical D&D Armor does not absorb damage but it instead deflects it.  This all or nothing principles has its origin in Iron Clad, a Civil-War battleship rules Dave Arneson worked on then adapted for D&D.  Now I've never been a big fan of this all or nothing approach, it works just fine for a battleship where a shell either pierces the hull or it doesn't but that's not how conventional worn armor works.  A while back during my crunch time posts I talked about one of the failures I had in Armor Class and trying to reverse Weapon vs AC.  A fool's bargain but it was an enlightening experience, now I would like to share the successor to that system which retains what I like most about OD&D's Armor, namely that the type of armor you wore was a class loose enough to be quick and abstracted and specific enough to account for different armor types.

Armor & Armor Class
There are three different classes of Armor: Light, Medium and Heavy which have an armor class of 1, 2 and 3 respectively.  Your armor class is a flat damage reduction against any incoming damage, if you are playing with a [Wounds] system then any damage dealt to Wounds takes priority.  Any damage to Wounds that is reduced by armor is converted to [Subdual] damage.  Should your Subdual damage plus any Wounds your character has taken exceeds the maximum amount of Wounds your character can receive they are rendered unconscious.

Now in order to differentiate Armor within a Class we have to add another mechanism, otherwise your armor types will be different in name only.  To do this we add a Favorable damage type for the armor.  Weapons and Armor follow a cycle where armor is produced specifically to counter the most common and/or most deadly weapon of the time.  This is true from the chainmail a fighting man wears all the way up to the Chobham armor of the M1 Abrams tank.  With a little research and intuition you can quickly come up with what a certain type of armor was particularly effective against.  Let's look at light armor first.  We'll look at three different types, Leather, Hide & Jack/Brigandine.

Brigandine, sometimes referred to as Jack was a many layered textile armor that was very adept at absorbing the impact of conventional ranged weapons, specifically the bow and arrow.  So for Brigandine we say that it is favorable towards Missile weapons, covering Bows, Crossbows, Javelins & Darts but not including throwing axes and the like.

Hide armor come from the hide of beasts and was very popular with Barbarian hordes.  The hide of a beast, especially its fur is very effective against the claws of other animals which would tear an unarmored man to shreds.  So Hide Armor is favorable against Slashing weapons.

Leather Armor is tanned hide, sometimes boiled in the case of cuir bouilli, often quite thick and sometimes studded with metal.  It is tight fitting and frequently composed of large singular pieces rather than segmented armor which has the advantage of dispersing force over a larger area.  In that case we would say that Leather armor is favorable against Impact weapons. 

We can repeat this exercise for other armors but in the meantime I will leave a table and the associated rules if you'd like to adapt this for your OSR games.  With the steps I outlined above you can certainly add more armor types to the list, throwing in variants like Studded leather and Laminar (Banded / Lorica Segmentata) or putting in exotic & expensive armors like the Linothorax and Ceannlann.


  • Armor Class reduces any incoming damage equal to its AC.
    • Damage dealt to Wounds takes first priority.
    • Wounds that are reduced by AC are converted to Subdual Damage
      • If the sum of your total Subdual Damage and Wounds taken exceeds the maximum amount of Wounds you can receive you are rendered unconscious.
    • The downside to Armor is that your Initiative is reduced by your AC.
  • If the armor is favorable to the damage type is first halves all incoming damage before applying it's AC to reduce the damage.
    • This armor system was designed with abstract d6 damage in mind.
      • Also that a Critical hit did 1d6 Wounds on top of regular damage.
      • If you are not playing with Wounds then a critical hit merely does an extra d6 of damage.
    • However, Plate Mail is invulnerable to non-impact weapons in a d6 only system.
      • As such two-handed weapons need to deal 2d6 damage.
      • Furthermore, certain weapons are more adept at piercing armor.  This will be covered later in the challenge.