Saturday, November 13, 2010

A Question of Nomenclature

In a system where 10 is the worst armor class, why does +2 chain mail decrease your AC?

8 comments:

Northy said...

Because some old-school players (like me!) enjoy confusing the young'uns and putting up the artificial barriers of entry that pretty basic math is to the annoying shouty ADD child types.

(Only half-way serious, I'm just feeling particularly Grognard today. I blame the fact that I spent three hours drawing up three more A3-sized dungeon floor plans. You're a bad influence on me, Joe!)

Jerry said...

I think there’s a note in the books somewhere saying to always interpret + as a betterment. Could be wrong about that, especially as I now note that the Defense Adjustment for Dexterity is given as +x making things worse and -x making things better.

Jesus, take a look at the wordplay in the description! “The penalty subtracts from the armor class… while the bonus adds to the defensive value of the character’s armor class”. In other words, the plus subtracts by making it larger and the minus adds by making it smaller.

I get rid of Armor Class in favor of a zero-based Defense in order to avoid explanations like that.

Because of dexterity, 10 is not the worst armor class. Low Dexterity can make it worse. Pity the Cleric with a 14 AC!

Talysman said...

Because people would interpret a minus as something bad, and because you're supposed to add it to your opponent's target number. Add weapon bonuses to the roll, defensive bonuses to the target, and it's not as confusing.

James Maliszewski said...

Because some old-school players (like me!) enjoy confusing the young'uns and putting up the artificial barriers of entry that pretty basic math is to the annoying shouty ADD child types.

My brother! ;-)

Matthew James Stanham said...

Because the nomenclature was originally developed for the Chain Mail armour class schema? Or perhaps to avoid confusion with other magical nomenclature, such as "sword +1"? Either way, as Talysman says, it is one of the few instances where the number is not added to the die roll, but increases the difficulty.

In some ways this is successful in distinguishing between a "better armour class" [i.e. 5 becomes 4] and a better defence. It is about the only real reason I can think of for favouring an ascending armour class system.

faoladh said...

Obviously, it doesn't decrease the protective value of your AC. It increases it. The AC number is decreased in proportion to the bonus of the magic affecting the armor. The precise reasons for that are obscure and largely lost to history, but that's what happened (we can, of course, speculate, as I do obliquely below). It works and there is no particular reason to change it.

People who like simplified or "rational" systems can just add the AC of the target and the attacker's bonuses to the roll in an attempt to hit whatever target number (say 20) or higher.

Mjolnir said...

Same reason you need to down a level to go up a level. It's a revealed gaming system. :D

longcoat000 said...

Actually, it depends on the edition. In 3LBB, the magical bonus subtracts from you opponent's effective level. So if a 4HD creature attacked a character wearing +2 chainmail, the creature would use the attack table of a 2HD creature attacking AC 5, not a 4HD creature attacking AC 3. It makes a difference because (I think) the monster attack tables go up every three hit dice.