Armour: AC vs DR [Archive] - Wizards Community

Armour: AC vs DR [Archive] - Wizards Community

Post/Author/DateTime Post
Nom
12-23-05, 08:30 AM I was thinking this afternoon about armour granting AC vs DR.

In D&D, armour grants AC, reducing the chance of an effective hit being scored. Some other systems treat armour as DR, providing a threshold which damage must overcome to apply to the wearer.

DR is a good way of modelling padding, or a defense where the armour lessens impact by absorbing it. In contrast, AC models a situation where your armour completely blocks some blows but provides minimal protection against blows that find weak spots.

According to some of our resident "experts", plate armours were generally capable of blocking most slashing and projectile weapons. Swinging a sword directly at plate was more likely to damage the sword rather than the target, so you aimed to either slash or stab at the weak points (such as anywhere that needed to be articulated).

For attacking through (rather than around) armour, maces and the like were used. Heavy-duty stabbing weapons were also an option. For a mace, the armour obviously has an absorbant effect. I'm not familiar enough with stabbing weapons vs armour to know whether there was much absorbant effect, or whether you either penetrated or you didn't. I suspect the latter.

From a modelling perspective, piercing or slashing weapons vs armour are thus better modelled as AC, possibly with a small DR component to represent absorbancy even of weak spots. In contrast, bludgeoning weapons vs armour are better modelled as DR; it's easier to hit (since you don't mind hitting armour), but the armour will attempt to absorb the blow.

Modelling primarily as DR does have another issue - what happens when a character can't penetrate the DR and thus attempts to strike at weak spots instead? To model this would require two AC values, one for strikes to the armour and one for strikes past it. The converse crops up for weaker armours and powerful slashing weapons. A decent sword strike could well penetrate straight through a light leather vest, but some power would be absorbed on the way.

At this stage, I'm not proposing any house rules or changes to the model, just expressing some initial thoughts. However, it does seem to me that armour as AC has a modelling advantage in that it models full protection well and will do as a model for absorbent armour (did your blow actually strike through with enough power or did the armour absorb it?), while armour as DR largely fails to deal with any model for striking around armour.

Your comments?
phelanarcetus
12-23-05, 10:13 AM The best I have seen for armor as DR is in the A Game of Thrones RPG. The basic premise behind that system is that to avoid armor's DR, you make a called shot. Take an attack penalty based on the armor's DR value to ignore part of the value. I figure that giving that amount of detail should be safe, but that I can't go into the exact rules (even if I remember them right). Alternately, the armor could specify the attack penalty seperately from its DR, if there's something that has very few weak points, but doesn't protect as well in general.

Now, I think we can't afford the added complexity of making armor have different behavior against different types of weapons. There's always a tradeoff between realism and logic on one side, and efficiency and simplicity on the other.

Modelling armor as AC is definitely simpler and more efficient - damage reduction becomes a special case that doesn't come up too often, and a successful attack merely needs to beat a fairly static AC value. Going full hack on realism, we would have a given armor granting different amounts of AC against different types of attacks, and different amounts of DR as well, and the defender would be rolling a defense check, and positioning and facing would come into it.

I think in D&D, making armor into DR, unless ACs/Defense scores get pretty high, really swings the advantage further towards the people with the big two-hander. One massive power attack landing does a hell of a lot of damage, and really doesn't care about the DR comparatively, while things like two-weapon fighting or archery really suffer when they lack significant bonus damage or the ability to consistently penetrate DR. Armor-based DR would not be something you could penetrate with a special material or enchantment, or else it would become worthless after a certain point.

Basically, I think that for D&D, the armor as AC system is appropriate. Using a different system would require changing a lot of other components of the overall game system, since balance decisions are based on the armor as AC system.
Nom
12-23-05, 04:08 PM I think in D&D, making armor into DR, unless ACs/Defense scores get pretty high, really swings the advantage further towards the people with the big two-hander. One massive power attack landing does a hell of a lot of damage, and really doesn't care about the DR comparatively, ...And every point of AC removed increases the PA potential by 2 points. If you stack on enough DR to counterbalance this, you make anyone in decent armour almost totally immune to lighter weapons unless you introduce a separate "bypass armour" AC.
Catra
12-23-05, 04:34 PM You're looking for a variant for AC/DR?

Take a trip to the Waking Lands (http://www.wakinglands.com/)
tiluvias99
12-23-05, 11:06 PM Take a look at my revised combat rules in my sig. It has everything you're thinking of, plus more.
Vahenir
12-24-05, 01:58 AM Everything you're looking for is in Mongoose Publishing's d20 Conan RPG. Best, most realistic but still simple armour vs. weapon system.. ever.
Nom
12-24-05, 07:56 AM Everything you're looking for is in Mongoose Publishing's d20 Conan RPG. Best, most realistic but still simple armour vs. weapon system.. ever.Rather than referring me to a sourcebook that I neither have nor have easy access to, perhaps you'd summarise your thoughts? I'm not actually wanting to change the existing rules, merely discuss the merits of different models of armour, both from the perspective of models and playability.
WhiteHarness
12-24-05, 04:50 PM I gotta agree with whoever said the Game of Thrones adaptation of the D&D rules models armour best. There armour rules are even better than the Mongoose Conan rules, Vahenir (and, incidentally, also written by Ian Sturrock). However, IIRC, the penalty for a called shot to bypass armour is *double* the armour's armour bonus, making it effective still at higher skill levels, IMO.
catzo
12-25-05, 01:15 PM You really should check out the Unearthed Arcana. It got lots of nice optional rules. ( DR/AC rules instance.)
Also for a more realistic D20 system, check out Grim & Gritty (http://www.rpgnow.com/product_info.php?products_id=5022) rules.
For an "as realistic as possible set of rules" take a look at GURPS (http://www.sjgames.com/). It´s a really great system, not D20 though. (Much better for anything realistic IMO :))

On the direct subject. I agree that the problem with DR is that it can often lead to situations where people in heavy armour are invulnerble. This is in fact one of the only reasons I like D&D over other systems (at times).
Also if you make armour give DR you need to give players not wearing DR something to compensate so you don´t end with situations where you have to wear armour to survive. (For the sake of gamebalance)

One of the suggestions by The Unearthed Arcana is to combine AC and DR. For armours take the AC/2 = DR. New AC = old AC-DR.
Nom
12-25-05, 06:31 PM One of the suggestions by The Unearthed Arcana is to combine AC and DR. For armours take the AC/2 = DR. New AC = old AC-DR.I'm not sure that this is such an improvement. It mitigates the scale of the problem, but doesn't really model weapons that either bypass the armour or are ineffective.

Post/Author/DateTime	Post
Nom 12-23-05, 08:30 AM	I was thinking this afternoon about armour granting AC vs DR. In D&D, armour grants AC, reducing the chance of an effective hit being scored. Some other systems treat armour as DR, providing a threshold which damage must overcome to apply to the wearer. DR is a good way of modelling padding, or a defense where the armour lessens impact by absorbing it. In contrast, AC models a situation where your armour completely blocks some blows but provides minimal protection against blows that find weak spots. According to some of our resident "experts", plate armours were generally capable of blocking most slashing and projectile weapons. Swinging a sword directly at plate was more likely to damage the sword rather than the target, so you aimed to either slash or stab at the weak points (such as anywhere that needed to be articulated). For attacking through (rather than around) armour, maces and the like were used. Heavy-duty stabbing weapons were also an option. For a mace, the armour obviously has an absorbant effect. I'm not familiar enough with stabbing weapons vs armour to know whether there was much absorbant effect, or whether you either penetrated or you didn't. I suspect the latter. From a modelling perspective, piercing or slashing weapons vs armour are thus better modelled as AC, possibly with a small DR component to represent absorbancy even of weak spots. In contrast, bludgeoning weapons vs armour are better modelled as DR; it's easier to hit (since you don't mind hitting armour), but the armour will attempt to absorb the blow. Modelling primarily as DR does have another issue - what happens when a character can't penetrate the DR and thus attempts to strike at weak spots instead? To model this would require two AC values, one for strikes to the armour and one for strikes past it. The converse crops up for weaker armours and powerful slashing weapons. A decent sword strike could well penetrate straight through a light leather vest, but some power would be absorbed on the way. At this stage, I'm not proposing any house rules or changes to the model, just expressing some initial thoughts. However, it does seem to me that armour as AC has a modelling advantage in that it models full protection well and will do as a model for absorbent armour (did your blow actually strike through with enough power or did the armour absorb it?), while armour as DR largely fails to deal with any model for striking around armour. Your comments?
phelanarcetus 12-23-05, 10:13 AM	The best I have seen for armor as DR is in the A Game of Thrones RPG. The basic premise behind that system is that to avoid armor's DR, you make a called shot. Take an attack penalty based on the armor's DR value to ignore part of the value. I figure that giving that amount of detail should be safe, but that I can't go into the exact rules (even if I remember them right). Alternately, the armor could specify the attack penalty seperately from its DR, if there's something that has very few weak points, but doesn't protect as well in general. Now, I think we can't afford the added complexity of making armor have different behavior against different types of weapons. There's always a tradeoff between realism and logic on one side, and efficiency and simplicity on the other. Modelling armor as AC is definitely simpler and more efficient - damage reduction becomes a special case that doesn't come up too often, and a successful attack merely needs to beat a fairly static AC value. Going full hack on realism, we would have a given armor granting different amounts of AC against different types of attacks, and different amounts of DR as well, and the defender would be rolling a defense check, and positioning and facing would come into it. I think in D&D, making armor into DR, unless ACs/Defense scores get pretty high, really swings the advantage further towards the people with the big two-hander. One massive power attack landing does a hell of a lot of damage, and really doesn't care about the DR comparatively, while things like two-weapon fighting or archery really suffer when they lack significant bonus damage or the ability to consistently penetrate DR. Armor-based DR would not be something you could penetrate with a special material or enchantment, or else it would become worthless after a certain point. Basically, I think that for D&D, the armor as AC system is appropriate. Using a different system would require changing a lot of other components of the overall game system, since balance decisions are based on the armor as AC system.
Nom 12-23-05, 04:08 PM	I think in D&D, making armor into DR, unless ACs/Defense scores get pretty high, really swings the advantage further towards the people with the big two-hander. One massive power attack landing does a hell of a lot of damage, and really doesn't care about the DR comparatively, ...And every point of AC removed increases the PA potential by 2 points. If you stack on enough DR to counterbalance this, you make anyone in decent armour almost totally immune to lighter weapons unless you introduce a separate "bypass armour" AC.
Catra 12-23-05, 04:34 PM	You're looking for a variant for AC/DR? Take a trip to the Waking Lands (http://www.wakinglands.com/)
tiluvias99 12-23-05, 11:06 PM	Take a look at my revised combat rules in my sig. It has everything you're thinking of, plus more.
Vahenir 12-24-05, 01:58 AM	Everything you're looking for is in Mongoose Publishing's d20 Conan RPG. Best, most realistic but still simple armour vs. weapon system.. ever.
Nom 12-24-05, 07:56 AM	Everything you're looking for is in Mongoose Publishing's d20 Conan RPG. Best, most realistic but still simple armour vs. weapon system.. ever.Rather than referring me to a sourcebook that I neither have nor have easy access to, perhaps you'd summarise your thoughts? I'm not actually wanting to change the existing rules, merely discuss the merits of different models of armour, both from the perspective of models and playability.
WhiteHarness 12-24-05, 04:50 PM	I gotta agree with whoever said the Game of Thrones adaptation of the D&D rules models armour best. There armour rules are even better than the Mongoose Conan rules, Vahenir (and, incidentally, also written by Ian Sturrock). However, IIRC, the penalty for a called shot to bypass armour is double the armour's armour bonus, making it effective still at higher skill levels, IMO.
catzo 12-25-05, 01:15 PM	You really should check out the Unearthed Arcana. It got lots of nice optional rules. ( DR/AC rules instance.) Also for a more realistic D20 system, check out Grim & Gritty (http://www.rpgnow.com/product_info.php?products_id=5022) rules. For an "as realistic as possible set of rules" take a look at GURPS (http://www.sjgames.com/). It´s a really great system, not D20 though. (Much better for anything realistic IMO :)) On the direct subject. I agree that the problem with DR is that it can often lead to situations where people in heavy armour are invulnerble. This is in fact one of the only reasons I like D&D over other systems (at times). Also if you make armour give DR you need to give players not wearing DR something to compensate so you don´t end with situations where you have to wear armour to survive. (For the sake of gamebalance) One of the suggestions by The Unearthed Arcana is to combine AC and DR. For armours take the AC/2 = DR. New AC = old AC-DR.
Nom 12-25-05, 06:31 PM	One of the suggestions by The Unearthed Arcana is to combine AC and DR. For armours take the AC/2 = DR. New AC = old AC-DR.I'm not sure that this is such an improvement. It mitigates the scale of the problem, but doesn't really model weapons that either bypass the armour or are ineffective.