Armor Class vs. Armor Classes

It is an inevitability that people needlessly demand expansions to the rules of a game for no good reason. They desire options and demand choice regardless of the (usually negative) impact on the rest of the system.

Armor Class in D&D is one such arena where being spoiled for choice worsens the game.

Today, we're all familiar with the bloated list of armor types and options available to players: padded, leather, studded leather, spiked armor, scale mail, halfplate, full plate, the list goes on and on for no real purpose (you're picking the one that gives you the biggest number).

Fewer options for armor is better. See:

The simplicity depicted here offers the reader a deeper apprehension of the term "Armor Class." Literally: a class of armor. Leather, chain, and plate are the three classes provided, with a fourth (no armor, or clothing) listed in another table. Shields provide an additional bonus but are not a class in their own right.

Armor Class thus becomes a descriptor and category of its own. Looking through the selection of monstrosities provided in B/X D&D, one can draw some inferences about Armor Class.

• Many animals, including apes (white), bats, bears (black, brown, grizzly), big cats (mountain lions, lions, tigers, and sabre-toothed tigers), dire wolves, rock baboons, and whales (killer, sperm) have an Armor Class of 6. We can infer that a thick hide provides an AC similar to leather or chain mail.

  
  

• Giant lizards (gecko and draco), lizardmen, crocodiles, and hydras all have Armor Class 5. This cements in my mind that scales (excluding those of the draconic variety) are equivalent to chain mail.

  
  

• Bone golems, giant crabs, giant scorpions, and driver ants all have AC 2, which is similar to plate. Triceratops, which are AC 2, are specifically called out as possessing a "bony protective crest" shielding its head. We can derive from this that rigid armors like bone, carapace, and shell roughly correspond to plate mail.

Now certain liberties are taken with these inferences. We know as monster Hit Dice (and monster size) increase, Armor Class decreases correspondingly. We also know that Armor Class considers monstrous agility and magical enhancement in this equation, which is why panthers have AC 4 compared to other big cats and wraiths, which wear no armor at all, have AC 3.

Imperfectly, I believe it is quite possible to derive a system describing Armor Classes as follows:

• Cloth or flesh: AC 9.

• Leather or hide armor: AC 7.

• Chain or scale: AC 5.

• Plate, shell, bone, or other rigid armors: AC 3.

One can thus adjust these numbers accordingly:

• Small and weak? Worsen AC by 1.

• Big and tough? Improve AC by 1.

• Swift and agile? Improve AC by 1.

• Magically enchanted? Improve AC by 1.

Supernatural Armor Classes are a trickier matter, but let us pass them by for now.

With this system of four easily-memorized key Armor Classes, the design space suddenly broadens immensely. Because we can simply assign a type of armor to a creature quickly and easily--or approximate the numerological specifics from its form--we can do things like provide weapons a variable damage or to-hit bonus against specific armor types.

This is virtually impossible in modern systems which have lists upon lists of armor, abandoning armor classes for armor numbers. As an example, see this chart from AD&D 2e:

This is useless at the table. I'm not using it. Neither are you.

However, compare that to a simplified form:

• Slashing weapons receive a +2 bonus vs. cloth or hide and a -2 against plate et al.

• Piercing weapons receive a +1 bonus vs. cloth, hide, chain, and scale.

• Bludgeoning weapons receive a +2 bonus vs. plate et al.

One can adjust these values as needed. (As the player characters are not likely to battle unarmored individuals, one could further simplify to a 3x3 matrix.)