I've always had a problem with Armor Class. I don't deny that it's a good mechanic to use for figuring combat results and measuring the varying protection that can be provided by different types of armor...but it's still silly. I understand perfectly why variant rules for different types of damage and a more specific Armor Class system weren't implemented into the core rulebooks...after all, combat takes long enough as it is. Adding even more depth to it isn't necessarily going to be something that everyone will love. That being said, I love complexity and realism (to a certain point...) in the games that I run. To that end I've drawn up a set of expanded rules for Armor Class. After a lot of play testing (and a lot of patience on the part of my players) I think I've got 'em just about perfect.
I'm going to start with the AC chain because that's really what started the whole mess. I've always been bothered by the way AC is presented in the core rulebooks. "If you roll this number or less on your attack roll you miss. If you beat it you hurt them." Simple? Yes. Realistic? Definitely not. I can accept that explanation for a defender in leather armor, but consider the case of Bracers of Armor. The description states that the Bracers generate a "magical field of force" which completely encompasses the wearer. If the field has no chinks or breaks into which a weapon can be slipped how, exactly, does a high attack roll hurt them? Does the weapon punch through the field? If so, shouldn't it have its damage reduced based on the strength of the field it passed through? Then there's full plate. That presents a whole other set of problems. I can deal with a rapier finding its way into the slits and joints of plate mail...but what about a greataxe? Surely THAT isn't being deftly guided into breaks in the armor?
My solution to this problem works to a certain extent but it tends to slow things down quite a bit...and it requires a lot of set up work. If you've got ideas on how to do this better I'd be interested in hearing them. My idea consists of two parts: the AC chain, and the armor damage rules.
Part 1: The AC Chain
The AC chain is actually a really simple idea which I still make use of for determining the outcome of attack rolls by both PCs and NPCs. Essentially, an AC chain is a point-by-point chart detailing where a character's total AC comes from. The reason this is important is that it lets you know what (if anything) an attacker did with his attack roll. Basically, you can compare an attack roll with the chart for a given defender and see that the attacker completely missed his target, or the defender dodged out of the way, or the attacker's claws raked across the front of the defender's breastplate. The AC chain itself is created simply by applying a ranking system to the various AC bonuses a character can receive. A character with every type of bonus (that I can think of right now) would look like this:
Base AC: A number in this range misses without the defender having to take any action.
Luck/Divine Bonus: Essentially an extension of Base AC. An attack roll that falls in this range requires no action on the part of the defender to miss.
Dex/Dodge Bonus: This attack would've struck the defender had he not been nimble enough to get out of the way.
Shield Bonus: This attack came too quickly for the defender to get out of the way, but slowly enough that he was able to block with his shield.
Armor Bonus: This attack gave the defender no chance to protect himself. All that saved him from damage was his armor.
Nat Armor Bonus: This attack bypassed all other defenses and was only stopped by the defender's natural toughness.
Thus, a paladin with a few magic items wearing full plate would look like this:
0-10 Base
11-12 Divine
13 Dex
14-15 Shield
16-23 Armor
An attacker who rolls a 15 will strike the paladin's shield, while a 17 would strike the paladin's armor. The net effect is the same as the regular AC rules, but it can help players (and the DM!) to visualize how a combat is unfolding.
Part 2: Armor Damage
Ever noticed how almost no one ever chooses to wear heavy armor? After all, why should you when you can receive the exact same protection by having a high Dexterity score and wearing light or no armor? Why burden yourself with 40-plus pounds of dead weight? It's because of this question (and a wistful urge to go back to the days when playing a knight in shining armor was still cool) that I've tried to even out the playing field between heavy and light armors. Be warned, however, that the following variant rules get pretty complex.
First, assign a hardness to each type of armor based upon its material composition. I strongly recommend using hardness 1 for leather and like materials and a hardness of 5 for steel. I know this doesn't match up with the hardnesses presented in the various core rulebooks but trust me, hardness 10 on full plate leads to absolutely ridiculous battles. For magical armor, add 1 to the hardness of the armor for every point of enhancement bonus.
Second, assign a damage threshold to each type of armor based upon its material composition and its construction. Damage threshold represents how many HP from a single blow a piece of armor can absorb before it is breached. I recommend using twice the armor's hardness for this value. Thus, leather would have a DT of 2 while steel would top out around 10.
Third, decide how many hit points a given suit of armor should have. The way I liked the most for doing this was to multiply an armor's AC bonus by 10. Thus, full plate has 80 HP, half plate has 70 HP, and so on. For magical armor, add 10 to the HP of the armor for every point of enhancement bonus.
Fourth, decide on a coverage rating for the armor. I've found that coverage ratings work best when you go by thirds of the body. In this way, breastplates and shirts have a CR of 2, shirts and greaves have a CR of 4, and full-body armors like full plate and full chain have a CR of 6. I arrived at these numbers after a lot of play testing. You're obviously welcome to try your own out, but going much higher than this tips the scales way too far in favor of heavy armor.
Finally, total up the AC of the defender and apply the armor's coverage rating to it. An armor's coverage rating can be looked at as a sort of phantom AC bonus that's added to the top of the AC chain. Whenever an attacker rolls higher than a defender's actual AC but below his phantom AC the weapon deals damage directly to the defender's armor and has a chance to punch through to the person wearing it. (Technically the attack should damage the armor on any roll that falls on the Armor Bonus section of the defender's AC chain but this tends to lead to armor falling apart after only a few fights.)
To determine if an attack is capable of punching through a defender's armor roll damage as normal, then subtract the armor's hardness from the damage roll. The resulting damage is subtracted from the HP of the armor up to its damage threshold. Anything left after that is dealt directly to the defender and is then subject to any damage reduction the character would normally be entitled to.
This adds a final category onto the end of our AC chain:
Phantom AC: An attack roll which falls within this category strikes with enough force to damage the armor of the defender and may (depending upon the force of the blow) punch through to damage the defender.
Thus, our paladin from before would have an AC chain that looks like this:
0-10 Base
11-12 Divine
13 Dex
14-15 Shield
16-23 Armor
24-29 Phantom
An attack roll of 27 would hit the paladin's armor with enough force to do damage. A damage roll of 16 would have its first 5 points negated by the armor's hardness. The next 10 points of damage would be absorbed by the armor's HP (reducing it from 80 to 70) and the final point would be dealt to the paladin himself. A few more blows like that and his armor will be nigh-unto useless.
Which leads us to the next logical step in this equation. As armor takes damage its effectiveness will obviously decrease. There are any number of different ways to describe this change in game terms, but I think the simplest and most realistic would be to base it off of a rough percentage. When armor reaches 50% of its total hit points reduce its AC bonus by half (rounding up) and apply a –2 to its armor check penalty. When armor reaches 0 hit points reduce its AC bonus by half again (round up; this will result in a net loss of 75%), apply an additional –2 to its armor check penalty (for a total of –4), subtract 2 from its maximum Dexterity bonus, and reduce its coverage rating by 1 step. These penalties represent the loss of mobility and coverage that come from severe damage to a suit of armor.
Yes, this means that a given suit of armor will, in a drawn out fight, be ruined fairly quickly. I recommend allowing PCs to make untrained (or trained, if they’ve got the tools and skills) repair checks. Based upon the amount of time and materials available, I recommend allowing repair checks to fix anywhere from 1 HP per 5 points rolled on a repair check to 1 HP per 1 point rolled on the check. That’s totally a DM-discretion kind of a thing, but I don’t recommend allowing a character to repair more than 50% of a suit of armor’s HP without proper training or tools, and I’d suggest making each check after the first progressively more difficult, forcing untrained characters to seek out the services of an armorsmith when one is available.
This last issue that I’ll address regarding the armor damage rules is one that hadn’t occurred to me until one of my players brought it up in play testing. Under the current AC rules there’s no system in place for layering armor, but with armor damage rules in effect the practice becomes much more tempting. Here’s my take on it.
First off, common sense should rule the day. You can’t wear a breastplate under a suit of full plate, but you could wear a chain or leather shirt. Even if you could, the added weight of the second suit of heavy armor would essentially immobilize most characters. To that end, I recommend allowing only light armors like padded, leather, and chain shirts to be worn underneath other armor (I would also disallow wearing 2 suits of light armor…no padded-beneath-leather combos). Normal bonus-stacking rules apply…which is to say, they don’t. A person wearing a leather shirt under half-plate would use the armor bonus from the half-plate alone. Similarly, the phantom AC bonuses from the two suits of armor overlap rather than stacking. Armor check penalties should stack and then have an additional –2 added to them. The maximum Dexterity bonus of the most restrictive armor should be used and then reduced by 2. This means that half-plate over leather provides the following stats: AC 7 and Max Dex –2. The benefits of wearing layered armor come into play when the defender’s armor suffers a hit. Let’s go back to the example of the paladin used above, but this time we’ll say he’s wearing leather armor under his full plate. His armor stats would thus be AC 8, Max Dex –1. Plate: CR 6, Hardness 5, DT 10, HP 80; Leather: CR 2, Hardness 1, DT 2, HP 80. His AC chain now looks like this:
0-9 Base (minus 1 for a low Dexterity)
10-11 Divine
12-13 Shield
14-22 Armor
23-24 Phantom (leather and plate)
25-28 Phantom (plate)
Our paladin is now slightly easier to hit in combat due to his reduced maneuverability; however, if he does take a hit it’s almost guaranteed not to cause him any physical damage. Say our attacker rolls a 24. This strikes with enough force to damage the paladin’s armor. The attacker rolls a 22 for damage. The first 5 points are absorbed by the plate’s hardness, then the next 10 points are dealt to its HP. This means that 7 points of damage made it through the plate armor. Next, the leather’s hardness absorbs 1 point of that damage and then 2 points are dealt to the leather’s HP, leaving 4 points of damage unaccounted for. Our paladin takes a meager 4 points of damage and is now ready to return fire. His armor now has 70 HP (plate) / 18 HP (leather).
Finally, we return to the Bracers of Armor and other similar items and effects like Mage Armor. I recommend treating these effects exactly like enhancement bonuses to normal armor but without the armor to back them up and without a hit point total to subtract damage from. Essentially, the hardness and damage threshold of these types of armor are the same thing. This way, Bracers of Armor +2 would have the following stats: AC +2, Hardness 2, Damage Threshold 4, and CR 6.
Like I said way back at the beginning, these rules are deeply involved. I don’t know how much use you’ll get out of them (especially the armor damage rules), but I’d be interested in hearing your opinions on them. I’m really fond of all of them, but the armor damage rules proved to be a little bit too cumbersome for my particular gaming group. The armor damage / phantom AC rules really add to the way heavy armor plays. In my mind it gives it a lot more value, making it much more realistic. Using these rules a knight in full plate is literally a walking tank…and isn’t that what full plate is really all about?
So what do you think? Good? Bad? Ugly?
-c
Expanded AC Rules
Moderators: DJ LaBoss, finarvyn, Harley Stroh
well, there is one advantage to wearing heavy armor under the current system... you're all flat footed untill your first action in a combat 
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i can't say that i would want to adopt the system, since it would add a lot of work, and the combats that my party gets involved in last 2-4 rounds, generally, and take one to two hours to complete as it is (no exageration
)
i do have a suggestion that you could take into consideration, though...
many armors take coverage into account already with thier current AC values, you might want to reduce the regular AC bonus for armors with alrge amounts of coverage
and, if you want to increase complexity another level, consider this: "slashing, piercing, bludgeoning"
you'd have to do some research, of course, but certain armors are more or less effective (IRL) against certain kinds of attacks... war picks like in the PHB were developed IRL to deal with platemail, for instance, and different materials perform differently when subjected to different attacks (metals are more likely to pass an attack that manages to puncture them, while organic materials will grab at whatever makes the puncture, though they are generally easier to puncture)
i might suggest that certain attack types should be able to ignore a certain amount of the armor's ability to stop damage when hit in the 'phantom' AC range...
i could also suggest that different weapon types are more or less likely to cause damage to an armor... a piercing attack would do nigligible damage to the overall structire of a suit of mail, and blugeoning attacks would be all but useless in damaging something made exclusively of cloth or leather
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i can't say that i would want to adopt the system, since it would add a lot of work, and the combats that my party gets involved in last 2-4 rounds, generally, and take one to two hours to complete as it is (no exageration
)i do have a suggestion that you could take into consideration, though...
many armors take coverage into account already with thier current AC values, you might want to reduce the regular AC bonus for armors with alrge amounts of coverage
and, if you want to increase complexity another level, consider this: "slashing, piercing, bludgeoning"
you'd have to do some research, of course, but certain armors are more or less effective (IRL) against certain kinds of attacks... war picks like in the PHB were developed IRL to deal with platemail, for instance, and different materials perform differently when subjected to different attacks (metals are more likely to pass an attack that manages to puncture them, while organic materials will grab at whatever makes the puncture, though they are generally easier to puncture)
i might suggest that certain attack types should be able to ignore a certain amount of the armor's ability to stop damage when hit in the 'phantom' AC range...
i could also suggest that different weapon types are more or less likely to cause damage to an armor... a piercing attack would do nigligible damage to the overall structire of a suit of mail, and blugeoning attacks would be all but useless in damaging something made exclusively of cloth or leather
ah, reese, i'm already way ahead of you. sort of. Expanded Weapon/Damage rules go up in a few minutes.
and yeah, you're right. i don't use the rules either. i like them, but they're way too cumbersome. the only thing that i do use is the AC Chain, but that's more just a tool to help with descriptive combats and helping the PCs understand just how a combat is going...it's very important to know whether that last attack whiffed past the Big Bad's face or whether it bounced off his armor-plated chest sometimes. i'm just posting them up to look for suggestions on improving them.
i hear you about long combats. they can take for -ever-, even without extra houserules. it's why we don't use these rules as written, but we do try to incorporate the idea of armor damage...usually after a few good hits the PC's armor starts to get a little worn and shabby and we'll apply an ad-hoc penalty to the AC bonus and the Max Dex, based on the armor type. makes the game more interesting, i think.
regarding the damage types though, think about this...
while bludgeoning weapons would have little to no effect on 'soft' armors like cloth, leather and flexible chain, the opposite is also true...shouldn't a man wearing padded armor actually be -more- likely to take damage from bludgeoning weapons than a guy in plate? think about it...bludgeoning damage needn't come from direct contact between the weapon and the defender...it can just as easily strike the 'soft' armor the defender is wearing and have almost all of its force carry through to inflict damage upon the wearer.
curioser and curioser.
-c
and yeah, you're right. i don't use the rules either. i like them, but they're way too cumbersome. the only thing that i do use is the AC Chain, but that's more just a tool to help with descriptive combats and helping the PCs understand just how a combat is going...it's very important to know whether that last attack whiffed past the Big Bad's face or whether it bounced off his armor-plated chest sometimes. i'm just posting them up to look for suggestions on improving them.
i hear you about long combats. they can take for -ever-, even without extra houserules. it's why we don't use these rules as written, but we do try to incorporate the idea of armor damage...usually after a few good hits the PC's armor starts to get a little worn and shabby and we'll apply an ad-hoc penalty to the AC bonus and the Max Dex, based on the armor type. makes the game more interesting, i think.
regarding the damage types though, think about this...
while bludgeoning weapons would have little to no effect on 'soft' armors like cloth, leather and flexible chain, the opposite is also true...shouldn't a man wearing padded armor actually be -more- likely to take damage from bludgeoning weapons than a guy in plate? think about it...bludgeoning damage needn't come from direct contact between the weapon and the defender...it can just as easily strike the 'soft' armor the defender is wearing and have almost all of its force carry through to inflict damage upon the wearer.
curioser and curioser.
-c
well, i figure that, as a rule of thumb, anything that causes less damage to a piece of armor will probably bypass that armor more easily in terms of dealing damage to a target
that's why i said that you might want to reduce teh amount of damage absorbed by the armor's HP for those types of attacks
(to use your example of the paladin, only 5 points instead of the full 10 would be absorbed by the armor when a piercing attack is used, and those 5 points not absorbed by the armor are, therefore, still applied to the player wearing the armor)
another point i just realized, this system makes armor slightly better at stopping physical attacks, which means that touch attacks become slightly more powerful (compared to regular attacks) when sued against armored foes
of course, any mage still has to close and make the touch attack, in most cases
that's why i said that you might want to reduce teh amount of damage absorbed by the armor's HP for those types of attacks
(to use your example of the paladin, only 5 points instead of the full 10 would be absorbed by the armor when a piercing attack is used, and those 5 points not absorbed by the armor are, therefore, still applied to the player wearing the armor)
another point i just realized, this system makes armor slightly better at stopping physical attacks, which means that touch attacks become slightly more powerful (compared to regular attacks) when sued against armored foes
of course, any mage still has to close and make the touch attack, in most cases
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goodmangames
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Definitely a little on the complex side... if the author doesn't use them, I won't feel bad about not using them, either. 
But I really like the AC chain idea. That's excellent. It should even be something displayed visually on the D&D character sheet... it definitely makes combat more interesting, makes descriptions easier, and opens the door for some new ideas.
But I really like the AC chain idea. That's excellent. It should even be something displayed visually on the D&D character sheet... it definitely makes combat more interesting, makes descriptions easier, and opens the door for some new ideas.actually, while i don't have any nice PDF versions, i like to include the AC chain on the back of most of my character sheets and encourage the PCs to do the same. most of 'em do, which is nice. it can help to explain why things work the way they do sometimes.
regarding the 'soft' armor discussion...i've never really tried to categorize armor by a hard/soft type before. huh. that could be a really solid way of doing that...could actually be the starting point of my next round of revisions to the Armor system...hmm...
-c
regarding the 'soft' armor discussion...i've never really tried to categorize armor by a hard/soft type before. huh. that could be a really solid way of doing that...could actually be the starting point of my next round of revisions to the Armor system...hmm...
-c
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mythfish
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We tried an experiment with an alternate AC system recently. We decided to take the term "hit" literally instead of meaning "to actually cause damage" and we made it so heavier armor actually makes you easier to hit, but we gave the heavier armor damage reduction ratings to represent the fact that it's harder to actually do damage to someone in plate. I still like the idea a lot in theory, but we had a hard time getting everything balanced correctly. After a couple sessions we decided to abandon the idea for the time being.
The AC chain is a really cool idea that I'll probably steal. One thing it does not take into account though, but probably could with minimal modification, is the fact that people who have trained to use their weapons tend to use them to parry as well. And as I understand it, the D&D system assumes that if a character is missed in combat, it is often because he has successfully blocked an incoming attack with his weapon (since D&D doesn't actually have any rules for parrying). So I might simply divide up the base into "1-5 Outright miss", "6-10 Parry" just to keep things more like I think actual combat is.
The AC chain is a really cool idea that I'll probably steal. One thing it does not take into account though, but probably could with minimal modification, is the fact that people who have trained to use their weapons tend to use them to parry as well. And as I understand it, the D&D system assumes that if a character is missed in combat, it is often because he has successfully blocked an incoming attack with his weapon (since D&D doesn't actually have any rules for parrying). So I might simply divide up the base into "1-5 Outright miss", "6-10 Parry" just to keep things more like I think actual combat is.
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mythfish
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Well, 1-10 seems like a pretty big range for outright missing. He hasn't dodged, since I didn't roll the dex bonus range, so he was just standing there three feet in front of me not moving at all, and I whiffed? It's really hard to miss someone if they're not actively trying not to get hit. So dividing the outright miss category in half appeals to me as well. 
Yeah, but I can see a real problem in the parrying version. What if you're not holding a weapon?
For instance, a mage holding a scroll in one hand and a wand in the other is attacked with a greatsword. I can just imagine the mage's player going "ha ha! I disarm you with my wand!" And I don't think that works.
But I can't think of anything better. The AC chain idea is really cool.
For instance, a mage holding a scroll in one hand and a wand in the other is attacked with a greatsword. I can just imagine the mage's player going "ha ha! I disarm you with my wand!" And I don't think that works.
But I can't think of anything better. The AC chain idea is really cool.
Last edited by Sword Guy on Mon Nov 29, 2004 8:21 pm, edited 1 time in total.
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Owner of all DragonMech books, Etherscope core book, and DCC 12.5: Iron Crypt of the Heretics.
well, it's not really a range of 1 to 10
most fighters, at level one, ahve a total bonus of +3
so, that means a range of 1 to 7 (approx 1 in 3)
and, if you define hitting as being able to deal damage, un-skilled users of a weapon can often hit in such a way as to deal no damage (flat of the blade, weak hit, hitting clothing)
at higher levels of AC and attack bonus, the chances of falling into the outright miss catagory are slim to none
a total attack bonus of +9 or better entierly negates it, in fact; many fighters have a bonus of +9 by level 4... +4 str, +4 BAB, +1 masterwork or magic
(note: anyone, anywhere, always has a 1 in 20 chance to miss an attack against an opponent that is not helpless, which is, in itself, unrealistic)
then again, the level of accuracy allowed to a player with ranged weapons is entierly unrealistic anyway (not to mention the range allowed!)
most fighters, at level one, ahve a total bonus of +3
so, that means a range of 1 to 7 (approx 1 in 3)
and, if you define hitting as being able to deal damage, un-skilled users of a weapon can often hit in such a way as to deal no damage (flat of the blade, weak hit, hitting clothing)
at higher levels of AC and attack bonus, the chances of falling into the outright miss catagory are slim to none
a total attack bonus of +9 or better entierly negates it, in fact; many fighters have a bonus of +9 by level 4... +4 str, +4 BAB, +1 masterwork or magic
(note: anyone, anywhere, always has a 1 in 20 chance to miss an attack against an opponent that is not helpless, which is, in itself, unrealistic)
then again, the level of accuracy allowed to a player with ranged weapons is entierly unrealistic anyway (not to mention the range allowed!)
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mythfish
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In that case logic wins and they just miss.Sword Guy wrote:Yeah, but I can see a real problem in the parrying version. What if you're not holding a weapon?
If they're not holding a weapon you'd obviously leave parrying out of the equation unless they're a fab unarmed combatant. Since characters' ACs can change during the course of a combat you'd have to alter their AC chains on the fly anyway.Good point. One of the things I just hate about the d20 system is its totally unrealistic combat system. But instead of going to all the work to make it more realistic, I tend to just play games that have more realistic systems when that's what I want.Reese wrote:a total attack bonus of +9 or better entierly negates it, in fact; many fighters have a bonus of +9 by level 4
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HackNslash
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I realize this topic has been dead for a couple months but I just read through it. The AC chain is a decent idea for DM's who don't feel creative with describing combat. However I think a simpler way to sovle armor damage would be to give each type of armor Hit points. When a hit is registered the damage done to the character will be as rolled. The armor would take the same damage minus its AC Bonus. If the armor is reduced by a certain percentage it would be considered needing repairs, further damage would lead to AC penalties and eventually leaving the Armor unrepairable.