Matthew
2009-06-06, 01:18 PM
This thread has been started to prevent further derailment of this thread: [4.0] Insults intelligence. (http://www.giantitp.com/forums/showthread.php?t=113706). Yeah, a bit edition war like, but THAC0 is actually a really interesting subject so I want to continue the discussion here. Much of the debate seems to hinge on two different definitions of Armour Class:
Armor Class A number representing a creature's ability to avoid being hit in combat.
Armor Class (abbr. AC)--a rating for the protective value of a type of armor, figured from 10 (no armor at all) to 0 or even -10 (the best magical armor). The higher the AC, the more vulnerable the character is to attack.
I have edited the subsequent exchanges to keep closer to the subject matter, omitting comments that I thought extraneous. Anyway, off we go... :smallbiggrin:
If you didn't motify THAC0 it wasn't that useful.
If you applied your strength modifier to your THAC0 and your magic weapon modifier to your THAC0, you reduce the math required to determine a hit to a single addition (or subtraction) of a single number.
Of course, you could do:
d20 + opponents AC + your to-hit bonuses
and see if it matched your THAC0. But that slowed the hit calculation down. :)
Nah, you apply all modifiers separately to avoid confusion. There is no speed difference in rolling a die and adding a modifier, but it depends how you do the actual in play event. I have heard of people saying stuff like "I hit AC 3", or something along those lines, instead of calling out their roll, in which case the calculation would need to be done before hand.
However, it can also work like this
Target Number = 21 (always)
Player: Rolls Dice, adds fighting ability and any other modifiers
Game Master: Adds armour class of target to the total, if it equals or exceeds 21 it is a hit.
The player can always know what AC he hits this way as well, of course [e.g. "19 isn't a hit? God damn, this thing has better than AC 2!"].
Alternatively, THAC0 eliminates fighting ability and becomes the target number, but all the player needs to do then is:
Target Number = THAC0
Player: Rolls dice and adds modifiers
Game master: Adds armour class of target and checks target number.
There is no difference in the second case, except transparency of the maths for the player [e.g. "15 isn't a hit? Hmmn, what's my THAC0 again? Oh yeah, 13, so it has better than AC −2?"]. However, the game master needs to have the unmodified THAC0 of all combatants written down in addition to their attack roll modifiers.
There are, in fact, some things which explicitly modify THAC0, such as the Weapons vs Armor Table.
Personally, I've always just used Roll higher than THAC0 - Armor Class, but there are many ways to do it. Really, though, I taught myself to play from a D&D introductory box when I was 5, and it used THAC0, so it certainly isn't anywhere near as incomprehensible as some people make it out to be.
The second edition one? Yeah, I think that optional rule is about the only instance. The more I think about it, the more convinced I am that the diversity of methods of calculation are in fact what leads people to believe it is "counter intuitive". Indeed, THAC0 could stand for the entire second edition game in that respect.
Reasons THAC0 was nonintuitive.
It was additive, rather than opposing. In other words, you added your opponent's AC to your attack roll. This essentially AC into more or less, a bonus/penalty to hit... And your skill as the goal. Shouldn't it be the other way around?
After all, the Armor Class, your opponent's defenses, are the obstacle. They're what you're trying to overcome. In the Thac0 system, you were trying to overcome your skill.
Contrast to 3.X, where Armor Class isn't a modifier, it's the final goal. In other words, it bases your hit ability around a single Armor Class, which is actually fairly rare. You needed to derive your actual success based on how hard it was to hit that one.
Now add in that armor that improved your AC by four lowered it, even while you added your AC to that attack roll. Magic swords also lowered your THAC0, but, due to the convoluted way it was set up, lowering your Thac0 makes it easier to hit, and lowering your AC makes it harder.
In other words, bonuses to hit modified the final difficulty, not the attack.
It's like saying that the wall is actually physically weaker because a master sniper is shooting at it... In the Thac0 system, you were modifying the target number, not your attack.
Do not not modify THAC0. That is why virtually everything is expressed as a modifier to the attack roll and not THAC0. The modifier is always the same [e.g. positive or negative], and that is why THAC0 works the way it does. Trying to modify THAC0 in AD&D is like trying to modify your opponent's armour class by your attack bonus in D20/3e.
Let's take an example:
A 5th level fighter with 17 strength has +1 to hit. He is also wielding a cursed sword, which is imposing a −1 to hit. In addition, his target is enjoying the effects of a prayer spell, imposing a further −1 to hit.
The player attacks his opponent and rolls a 13, which he modifies by −1 to get 12. The game master checks the armour class of his opponent, which is 5 and adds it to the result to get 17, which is better than his THAC0 of 16. A hit has been scored.
In this instance, the player was told there was a prayer effect in play and asked to modify his attack roll accordingly. If the game master had wanted to keep that secret, then he could have applied the same modifier to the armour class of the target.
As opposed to the following:
A 5th level fighter with a 17 strength has a +9 to hit. He has a bane effect on him, imposing a -1 to attack rolls. In addition, his target has declared him a dodge target, which increases the target's AC by one.
The fighter rolls, and gets a 13. He looks to the DM, and says "I hit AC 22." (13+9) The DM compares it to the AC of the target (20), adds 1 for the dodge (player doesn't have that knowledge), and declares the hit.
In this way, the DM, as storyteller/mediator, is letting players control player information, and handling privately only the information that players are not privy to. He doesn't need to know the Thac0 of his players. Only the roll, and the modifiers that players are not privy to. Simple.
And yet, the DM still has to look at a player sheet, and a monster sheet, to determine the hit. The DM has to process the number and compare to a player number. Whereas, in 3.x, the DM compares the player number only against the privy information. Each player can handle more of the equation, and the DM is left mediating the information that isn't.
It's the same process:
Roll die, player modifiers added, game master modifiers added = THAC0?
Roll die, player modifiers added, game master modifiers added = Armour Class?
The only difference are that the game master almost always adds a modifier by way of armour class in AD&D, and that in D20 the modifiers are typically much larger. The trade off is that in AD&D negative modifiers are always good for the defender, and positive modifiers always good for the attacker.
If the game master needs to look at the player sheet it means he does not have their THAC0 already available, but he should have their THAC0s and that of all the combatants in play available, just like he should have their armour classes available in D20. That is not extra math, it is just like having BAB noted separately from AB.
Well, that in every edition after thac0, bonuses added, and penalties subtracted. Rather than having to remember whether this is a bonus that added to this score, or it was a bonus that subtracted from that one. Counter-intuitive.
Again you misunderstand. You are assuming these terms:
My plusses are good for me
My minuses are bad for me
His pluses are bad for me
His minuses are good for me
In AD&D it is:
Plusses against him are good for me
Minuses against him are good for me
Plusses against me are bad for me
Minuses against me are bad for me
Neither is more intuitive than the other.
Or, he has 17 creatures to keep track of already... Why not let the players handle their own bonuses, rather than ensuring that they will always have an unknown modifier in the form of AC... Which would be more easily expressed by making it the target number. That way, in many fights, the PC could handle most of the work. As is, the DM, in AD&D ALWAYS has to add in a modifier before comparing. Always. In 3.x and beyond? If there are no surprises? He can just look at the two numbers. This reduction in variables streamlines combat, and makes things move faster. That's a good thing.
Not always, of course, not on AC 0. However, I do not really think that you can make the case that there are typically less modifiers in D20 than AD&D.
I assume:
Plusses are good for the roll.
Minuses are bad for the roll.
Plusses increase things.
Minuses decrease things.
AD&D assumes:
Plusses are good for the roll... unless they're to AC, when they're bad for the roll.
Plusses increase things... With the exception of this and that and the other.
Pluses to the roll in AD&D are good for the person rolling the die, minuses to the roll are bad for the person rolling the die. Same in D20.
Intuitive is when Plusses add, and minuses subtract. Intuitive is when 5 is better than 4.
Intuitive is when the AC system doesn't start with a number as completely arbitrary as whether the MacGuffin is a book or a badger.
Thac0 cheerfully says no to all of these.
No, just that the ones that are there are not modifiers. The AC of your foe is the whole goal. That's the resistance you're overcoming. Beat the AC, accomplish the goal.
In football, if you overcome your opponent's defense? It's a touchdown.
In hockey or soccer? Goal.
But in AD&D, there is no overcoming defenses. There's overcoming your Thac0. The sports? Intuitive. The Thac0? NOT.
This initial idea that Armour Class is a number to be overcome, rather than a modifier to a roll. That is completely non intuitive, since "armour class" does not denote that at all except by learned exposure. If it were called "defence rating" you might have a point.
A rose by any other name. Naming differences aren't the issue here. The fact that Armor Class combines (in all discussed editions):
Bonuses from armor
Bonuses from agility
Bonuses from magic
Miscellaneous other Bonuses
Shows that regardless of what you call it, what it actually IS, is a measure of a character's ability to dodge/block/parry or otherwise avoid being hit.
In other words, whether it's called armor class or defense rating, it IS a rating of the character's defense.
On what basis do you conclude that armour class is a number to be overcome when in fact it only is in D20? That is purely subjective on your part. In Chainmail, for instance, Armour Class is a number cross referenced against Weapon Class to find the probability of a kill on the man to man melee table.
Armour classification is just that, the class of armour. You add it to the attack roll (or deduct it from THAC0 if you prefer). This is the sort of statement that leads me to infer that you are are unfamiliar with the design approach of AD&D, in that you are imposing the conceits of D20 onto the game system and coming to an erroneous conclusion.
The above list of bonuses makes no case at all. These are all modifiers to the attack roll and not bonuses to a number to be overcome.
Let's say I have a suit of armor. It's magical +1.
There's a bonus to AC from armor.
There's a bonus to AC from magic.
Now let's say I have an 18 dexterity.
There's a bonus to AC from agility.
All three of these apply in both 2ed and 3ed (and 4ed).
So NO. Armor Class is not just your class of armor. It also factors in your ability to dodge, at the very least.
That is actually wrong. Magic and dexterity do not give a bonus to armour class, they impose negative penalties on the attack roll. You can roll them into armour class (which is commonly done), but that is not the actual armour class (which is a number in AD&D used to find bonuses to hit versus weapon type).
So it's more.
In other words, your assertation is incorrect. Because Armor Class is NOT "just that". Because your dexterity is not armor, even though it modifies armor class. Armor Class is an abstract concept, representing how hard you are to hit.
Yeah, it is just that. The "modified" armour class is a short handed rolling up of bonuses and penalties to make the game go more quickly, but armour class is literally class of armour.
Incorrect. AGAIN. AC is a number. A Classification of armor? Then why did the AD&D tarrasque (who, as far as I can tell, was not wearing chain greaves) sport a -10?
No. Direct from the owners of the game:
That's not the Classification of armor. No, Armor class was a derived term, true. But not from AD&D. No. It was from a tactical Civil War naval combat game, when it actually did represent how well armored ships were.
Wrong, I am afraid. Armour Class is right there in Chainmail, but reversed so that higher is better. Arneson is reported to have taken inspiration from the Naval game, but armour class was already part of the Chainmail Combat system. There is a reason that hit charts in OD&D only go down to AC 2 despite the presence of magic items.
But it means something different. Don't like that? Sorry. But the people who make the game disagree with you.
You're wrong.
Nope, the charts were extended in AD&D (and in Greyhawk) for ease of play, but the actual "rolling up" process is not armour class in its primary sense, though "armour class" is used to denote the secondary meaning in almost all short handed instances. The difference is important when you are dealing with the repeating "20" rule or when using weapon type versus armour class.
I can't believe it. I show you verbatim word for word, from the owners of the game, text that directly contradicts you... And you STILL refuse to see it!?
Yeah, I'm done here. Have fun with your... Well, with whatever it is you do.
Here is the original wording:
Monsters & Treasure, p. 31:
ARMOR: Armor proper subtracts its bonus [Note: here we are talking magical bonus] from the hit dice of the opponents of its wearer. If the shield's bonus is greater than that of the armor there is a one third chance that the blow will be caught by the shield, thus giving the additional subtraction.
That notes armor. Not armor class.
Show me some sort of specific text that states that Armor Class only measures the effectiveness of the armor that is worn, and counts in no other factors, or retract your point.
There are two types of armour class. There is:
a) The Armour Type's Armour Class.
Armour protection is measured by Armour Class (AC), a number rating; the lower the Armour Class number, the better the protection.
Armor Class (abbr. AC)--a rating for the protective value of a type of armor, figured from 10 (no armor at all) to 0 or even -10 (the best magical armor). The higher the AC, the more vulnerable the character is to attack.
b) The Modified Amour Class of the defender.
Defensive Adjustment applies to a character's saving throws (see Glossary) against attacks that can be dodged--lightning bolts, boulders, etc. It also modifies the character's Armor Class (see Glossary), representing his ability to dodge normal missiles and parry weapon thrusts. For example, Rath is wearing chain mail, giving him an Armor Class of 5. If his Dexterity score is 16, his Armor Class is modified by -2 to 3, making him harder to hit. If his Dexterity score is 5, his Armor Class is modified by +2 to 7, making him
easier to hit. (In some situations, beneficial Dexterity modifiers to Armor Class do not apply. Usually this occurs when a character is attacked from behind or when his movement is restricted--attacked while prone, tied up, on a ledge, climbing a rope, etc.)
The former is important for such things as weapon type versus armour class and the "repeating 20" rule in AD&D. It is also important for magic nullifying effects, and attacks from the flanks that negate benefits from dexterity or shield.
Now here is the exchange in question:
Let's say I have a suit of armour. It's magical +1.
There's a bonus to AC from armour.
There's a bonus to AC from magic.
Now let's say I have an 18 dexterity.
There's a bonus to AC from agility.
All three of these apply in both 2ed and 3ed (and 4ed).
So NO. Armour Class is not just your class of armour. It also factors in your ability to dodge, at the very least.
That is actually wrong. Magic and dexterity do not give a bonus to armour class, they impose negative penalties on the attack roll. You can roll them into armour class (which is commonly done), but that is not the actual armour class (which is a number in AD&D used to find bonuses to hit versus weapon type).
I can see that this has caused some confusion. My intention was to distinguish here between two forms of armour class. The base armour class is determined by armour type (used for weapon type versus armour class adjustments, if used) and the short hand that rolls all modifiers into a defensive value also termed "armour class". Armour Type is not a bonus to "armour class", it is the "base armour class" ranging from 10 to 0. Take your example for instance:
Plate Mail +1 (say) = AC 3(2)
Dexterity 18 = −4
Modified Armour Class = −2
A first level fighter needs "20" to hit that Armour Class in second edition, but if he has a +1 sword he doesn't suddenly need "19". He still needs "20" because the modified armour class deducts from his "to hit" roll. That's why armour itself only has a base classification system between 0 and 10.
Armor Class A number representing a creature's ability to avoid being hit in combat.
Armor Class (abbr. AC)--a rating for the protective value of a type of armor, figured from 10 (no armor at all) to 0 or even -10 (the best magical armor). The higher the AC, the more vulnerable the character is to attack.
I have edited the subsequent exchanges to keep closer to the subject matter, omitting comments that I thought extraneous. Anyway, off we go... :smallbiggrin:
If you didn't motify THAC0 it wasn't that useful.
If you applied your strength modifier to your THAC0 and your magic weapon modifier to your THAC0, you reduce the math required to determine a hit to a single addition (or subtraction) of a single number.
Of course, you could do:
d20 + opponents AC + your to-hit bonuses
and see if it matched your THAC0. But that slowed the hit calculation down. :)
Nah, you apply all modifiers separately to avoid confusion. There is no speed difference in rolling a die and adding a modifier, but it depends how you do the actual in play event. I have heard of people saying stuff like "I hit AC 3", or something along those lines, instead of calling out their roll, in which case the calculation would need to be done before hand.
However, it can also work like this
Target Number = 21 (always)
Player: Rolls Dice, adds fighting ability and any other modifiers
Game Master: Adds armour class of target to the total, if it equals or exceeds 21 it is a hit.
The player can always know what AC he hits this way as well, of course [e.g. "19 isn't a hit? God damn, this thing has better than AC 2!"].
Alternatively, THAC0 eliminates fighting ability and becomes the target number, but all the player needs to do then is:
Target Number = THAC0
Player: Rolls dice and adds modifiers
Game master: Adds armour class of target and checks target number.
There is no difference in the second case, except transparency of the maths for the player [e.g. "15 isn't a hit? Hmmn, what's my THAC0 again? Oh yeah, 13, so it has better than AC −2?"]. However, the game master needs to have the unmodified THAC0 of all combatants written down in addition to their attack roll modifiers.
There are, in fact, some things which explicitly modify THAC0, such as the Weapons vs Armor Table.
Personally, I've always just used Roll higher than THAC0 - Armor Class, but there are many ways to do it. Really, though, I taught myself to play from a D&D introductory box when I was 5, and it used THAC0, so it certainly isn't anywhere near as incomprehensible as some people make it out to be.
The second edition one? Yeah, I think that optional rule is about the only instance. The more I think about it, the more convinced I am that the diversity of methods of calculation are in fact what leads people to believe it is "counter intuitive". Indeed, THAC0 could stand for the entire second edition game in that respect.
Reasons THAC0 was nonintuitive.
It was additive, rather than opposing. In other words, you added your opponent's AC to your attack roll. This essentially AC into more or less, a bonus/penalty to hit... And your skill as the goal. Shouldn't it be the other way around?
After all, the Armor Class, your opponent's defenses, are the obstacle. They're what you're trying to overcome. In the Thac0 system, you were trying to overcome your skill.
Contrast to 3.X, where Armor Class isn't a modifier, it's the final goal. In other words, it bases your hit ability around a single Armor Class, which is actually fairly rare. You needed to derive your actual success based on how hard it was to hit that one.
Now add in that armor that improved your AC by four lowered it, even while you added your AC to that attack roll. Magic swords also lowered your THAC0, but, due to the convoluted way it was set up, lowering your Thac0 makes it easier to hit, and lowering your AC makes it harder.
In other words, bonuses to hit modified the final difficulty, not the attack.
It's like saying that the wall is actually physically weaker because a master sniper is shooting at it... In the Thac0 system, you were modifying the target number, not your attack.
Do not not modify THAC0. That is why virtually everything is expressed as a modifier to the attack roll and not THAC0. The modifier is always the same [e.g. positive or negative], and that is why THAC0 works the way it does. Trying to modify THAC0 in AD&D is like trying to modify your opponent's armour class by your attack bonus in D20/3e.
Let's take an example:
A 5th level fighter with 17 strength has +1 to hit. He is also wielding a cursed sword, which is imposing a −1 to hit. In addition, his target is enjoying the effects of a prayer spell, imposing a further −1 to hit.
The player attacks his opponent and rolls a 13, which he modifies by −1 to get 12. The game master checks the armour class of his opponent, which is 5 and adds it to the result to get 17, which is better than his THAC0 of 16. A hit has been scored.
In this instance, the player was told there was a prayer effect in play and asked to modify his attack roll accordingly. If the game master had wanted to keep that secret, then he could have applied the same modifier to the armour class of the target.
As opposed to the following:
A 5th level fighter with a 17 strength has a +9 to hit. He has a bane effect on him, imposing a -1 to attack rolls. In addition, his target has declared him a dodge target, which increases the target's AC by one.
The fighter rolls, and gets a 13. He looks to the DM, and says "I hit AC 22." (13+9) The DM compares it to the AC of the target (20), adds 1 for the dodge (player doesn't have that knowledge), and declares the hit.
In this way, the DM, as storyteller/mediator, is letting players control player information, and handling privately only the information that players are not privy to. He doesn't need to know the Thac0 of his players. Only the roll, and the modifiers that players are not privy to. Simple.
And yet, the DM still has to look at a player sheet, and a monster sheet, to determine the hit. The DM has to process the number and compare to a player number. Whereas, in 3.x, the DM compares the player number only against the privy information. Each player can handle more of the equation, and the DM is left mediating the information that isn't.
It's the same process:
Roll die, player modifiers added, game master modifiers added = THAC0?
Roll die, player modifiers added, game master modifiers added = Armour Class?
The only difference are that the game master almost always adds a modifier by way of armour class in AD&D, and that in D20 the modifiers are typically much larger. The trade off is that in AD&D negative modifiers are always good for the defender, and positive modifiers always good for the attacker.
If the game master needs to look at the player sheet it means he does not have their THAC0 already available, but he should have their THAC0s and that of all the combatants in play available, just like he should have their armour classes available in D20. That is not extra math, it is just like having BAB noted separately from AB.
Well, that in every edition after thac0, bonuses added, and penalties subtracted. Rather than having to remember whether this is a bonus that added to this score, or it was a bonus that subtracted from that one. Counter-intuitive.
Again you misunderstand. You are assuming these terms:
My plusses are good for me
My minuses are bad for me
His pluses are bad for me
His minuses are good for me
In AD&D it is:
Plusses against him are good for me
Minuses against him are good for me
Plusses against me are bad for me
Minuses against me are bad for me
Neither is more intuitive than the other.
Or, he has 17 creatures to keep track of already... Why not let the players handle their own bonuses, rather than ensuring that they will always have an unknown modifier in the form of AC... Which would be more easily expressed by making it the target number. That way, in many fights, the PC could handle most of the work. As is, the DM, in AD&D ALWAYS has to add in a modifier before comparing. Always. In 3.x and beyond? If there are no surprises? He can just look at the two numbers. This reduction in variables streamlines combat, and makes things move faster. That's a good thing.
Not always, of course, not on AC 0. However, I do not really think that you can make the case that there are typically less modifiers in D20 than AD&D.
I assume:
Plusses are good for the roll.
Minuses are bad for the roll.
Plusses increase things.
Minuses decrease things.
AD&D assumes:
Plusses are good for the roll... unless they're to AC, when they're bad for the roll.
Plusses increase things... With the exception of this and that and the other.
Pluses to the roll in AD&D are good for the person rolling the die, minuses to the roll are bad for the person rolling the die. Same in D20.
Intuitive is when Plusses add, and minuses subtract. Intuitive is when 5 is better than 4.
Intuitive is when the AC system doesn't start with a number as completely arbitrary as whether the MacGuffin is a book or a badger.
Thac0 cheerfully says no to all of these.
No, just that the ones that are there are not modifiers. The AC of your foe is the whole goal. That's the resistance you're overcoming. Beat the AC, accomplish the goal.
In football, if you overcome your opponent's defense? It's a touchdown.
In hockey or soccer? Goal.
But in AD&D, there is no overcoming defenses. There's overcoming your Thac0. The sports? Intuitive. The Thac0? NOT.
This initial idea that Armour Class is a number to be overcome, rather than a modifier to a roll. That is completely non intuitive, since "armour class" does not denote that at all except by learned exposure. If it were called "defence rating" you might have a point.
A rose by any other name. Naming differences aren't the issue here. The fact that Armor Class combines (in all discussed editions):
Bonuses from armor
Bonuses from agility
Bonuses from magic
Miscellaneous other Bonuses
Shows that regardless of what you call it, what it actually IS, is a measure of a character's ability to dodge/block/parry or otherwise avoid being hit.
In other words, whether it's called armor class or defense rating, it IS a rating of the character's defense.
On what basis do you conclude that armour class is a number to be overcome when in fact it only is in D20? That is purely subjective on your part. In Chainmail, for instance, Armour Class is a number cross referenced against Weapon Class to find the probability of a kill on the man to man melee table.
Armour classification is just that, the class of armour. You add it to the attack roll (or deduct it from THAC0 if you prefer). This is the sort of statement that leads me to infer that you are are unfamiliar with the design approach of AD&D, in that you are imposing the conceits of D20 onto the game system and coming to an erroneous conclusion.
The above list of bonuses makes no case at all. These are all modifiers to the attack roll and not bonuses to a number to be overcome.
Let's say I have a suit of armor. It's magical +1.
There's a bonus to AC from armor.
There's a bonus to AC from magic.
Now let's say I have an 18 dexterity.
There's a bonus to AC from agility.
All three of these apply in both 2ed and 3ed (and 4ed).
So NO. Armor Class is not just your class of armor. It also factors in your ability to dodge, at the very least.
That is actually wrong. Magic and dexterity do not give a bonus to armour class, they impose negative penalties on the attack roll. You can roll them into armour class (which is commonly done), but that is not the actual armour class (which is a number in AD&D used to find bonuses to hit versus weapon type).
So it's more.
In other words, your assertation is incorrect. Because Armor Class is NOT "just that". Because your dexterity is not armor, even though it modifies armor class. Armor Class is an abstract concept, representing how hard you are to hit.
Yeah, it is just that. The "modified" armour class is a short handed rolling up of bonuses and penalties to make the game go more quickly, but armour class is literally class of armour.
Incorrect. AGAIN. AC is a number. A Classification of armor? Then why did the AD&D tarrasque (who, as far as I can tell, was not wearing chain greaves) sport a -10?
No. Direct from the owners of the game:
That's not the Classification of armor. No, Armor class was a derived term, true. But not from AD&D. No. It was from a tactical Civil War naval combat game, when it actually did represent how well armored ships were.
Wrong, I am afraid. Armour Class is right there in Chainmail, but reversed so that higher is better. Arneson is reported to have taken inspiration from the Naval game, but armour class was already part of the Chainmail Combat system. There is a reason that hit charts in OD&D only go down to AC 2 despite the presence of magic items.
But it means something different. Don't like that? Sorry. But the people who make the game disagree with you.
You're wrong.
Nope, the charts were extended in AD&D (and in Greyhawk) for ease of play, but the actual "rolling up" process is not armour class in its primary sense, though "armour class" is used to denote the secondary meaning in almost all short handed instances. The difference is important when you are dealing with the repeating "20" rule or when using weapon type versus armour class.
I can't believe it. I show you verbatim word for word, from the owners of the game, text that directly contradicts you... And you STILL refuse to see it!?
Yeah, I'm done here. Have fun with your... Well, with whatever it is you do.
Here is the original wording:
Monsters & Treasure, p. 31:
ARMOR: Armor proper subtracts its bonus [Note: here we are talking magical bonus] from the hit dice of the opponents of its wearer. If the shield's bonus is greater than that of the armor there is a one third chance that the blow will be caught by the shield, thus giving the additional subtraction.
That notes armor. Not armor class.
Show me some sort of specific text that states that Armor Class only measures the effectiveness of the armor that is worn, and counts in no other factors, or retract your point.
There are two types of armour class. There is:
a) The Armour Type's Armour Class.
Armour protection is measured by Armour Class (AC), a number rating; the lower the Armour Class number, the better the protection.
Armor Class (abbr. AC)--a rating for the protective value of a type of armor, figured from 10 (no armor at all) to 0 or even -10 (the best magical armor). The higher the AC, the more vulnerable the character is to attack.
b) The Modified Amour Class of the defender.
Defensive Adjustment applies to a character's saving throws (see Glossary) against attacks that can be dodged--lightning bolts, boulders, etc. It also modifies the character's Armor Class (see Glossary), representing his ability to dodge normal missiles and parry weapon thrusts. For example, Rath is wearing chain mail, giving him an Armor Class of 5. If his Dexterity score is 16, his Armor Class is modified by -2 to 3, making him harder to hit. If his Dexterity score is 5, his Armor Class is modified by +2 to 7, making him
easier to hit. (In some situations, beneficial Dexterity modifiers to Armor Class do not apply. Usually this occurs when a character is attacked from behind or when his movement is restricted--attacked while prone, tied up, on a ledge, climbing a rope, etc.)
The former is important for such things as weapon type versus armour class and the "repeating 20" rule in AD&D. It is also important for magic nullifying effects, and attacks from the flanks that negate benefits from dexterity or shield.
Now here is the exchange in question:
Let's say I have a suit of armour. It's magical +1.
There's a bonus to AC from armour.
There's a bonus to AC from magic.
Now let's say I have an 18 dexterity.
There's a bonus to AC from agility.
All three of these apply in both 2ed and 3ed (and 4ed).
So NO. Armour Class is not just your class of armour. It also factors in your ability to dodge, at the very least.
That is actually wrong. Magic and dexterity do not give a bonus to armour class, they impose negative penalties on the attack roll. You can roll them into armour class (which is commonly done), but that is not the actual armour class (which is a number in AD&D used to find bonuses to hit versus weapon type).
I can see that this has caused some confusion. My intention was to distinguish here between two forms of armour class. The base armour class is determined by armour type (used for weapon type versus armour class adjustments, if used) and the short hand that rolls all modifiers into a defensive value also termed "armour class". Armour Type is not a bonus to "armour class", it is the "base armour class" ranging from 10 to 0. Take your example for instance:
Plate Mail +1 (say) = AC 3(2)
Dexterity 18 = −4
Modified Armour Class = −2
A first level fighter needs "20" to hit that Armour Class in second edition, but if he has a +1 sword he doesn't suddenly need "19". He still needs "20" because the modified armour class deducts from his "to hit" roll. That's why armour itself only has a base classification system between 0 and 10.