Armour as DR

[Jeivar]

I was just wondering if people have experimented with this: Making armour purely about damage reduction, and your defence against getting hit something like (Dexterity modifier + Shield + Proficiency Bonus).

[Zhorn]

Not against the idea; but just playing devil's advocate here;
Unless you rework the numbers no how much AC is worth and the attack damage of weapons, this could easily fall into the trap of making it impossible for some enemies to actually cause any damage even when they land a hit.
It also turns attack damage from a usually 2 step process (resolve hit, resolve damage) to a 3 step process (resolve hit, resolve damage rolled, resolve damage reduction).

To implement a system like this, how would you define the expected values of each part so we can get an idea of what numbers would be considered standard?

Avoidance = Dexterity modifier + Shield + Proficiency Bonus
is the shield still a +2, or is it a different value?
is the to hit modifier still including ability modifier and proficiency bonus?


AC = DR
What number range per armor type?


Damage rolls: ?
Still using the same damage dice and modifiers?

[Bjarkmundur]

Haven't tried it, no, but I've seen some threads about it. To not have to rewrite the entire game, you'd have to make some pretty general rules, and round off a lot of numbers. It won't be accurate, but it'll be playable (maybe).

Take the difference between your attack bonus and the target AC and divide that number by 20. That's your hit chance. Now take the average damage output of the attacker, and multiply it by that number.

+4 attack vs 14 AC, 10 damage on hit.
14-4 = 10
10/20 = 0.5
An AC of 14 against an attack of +4 results in taking 5 automatic damage.

You can use this to create a table:

Difference of 0 = 0% DR +14 vs 14 AC = 10 damage
Difference of 1 = 5% DR
Difference of 2 = 10% DR
Difference of 3 = 15% DR
Difference of 4 = 20% DR
Difference of 5 = 25% DR +4 vs 14 AC with advantage = 7 damage (because 5e rounds down)
Difference of 6 = 30% DR
Difference of 7 = 35% DR
Difference of 8 = 40% DR
Difference of 9 = 45% DR
Difference of 10 = 50% DR +4 vs 14 AC = 5 damage
Difference of 11 = 55% DR
Difference of 12 = 60% DR
Difference of 13 = 65% DR
Difference of 14 = 70% DR
Difference of 15 = 75% DR +4 vs 14 AC with disadvantage = 2 damage (because 5e rounds down)
Difference of 16 = 80% DR
Difference of 17 = 85% DR
Difference of 18 = 90% DR
Difference of 19 = 95% DR +4 vs 23 AC = 0 damage (because 5e rounds down)
Difference of 20 = 100% DR

This is an oversimplification to show how such a mechanic would work. Advantage would have to be reskinned into a +5 attack.
And you'd need a calculator.
Crits and fumbles no longer exist, since those are based off a roll and are not included in the math or balance of 5e.
Don't use flanking, since it's likely to favor the enemy, and advantage suddenly gives you a 25% damage bonus.

If you're asking about flat DR, then no, I don't think that'll ever work. Grod did an interesting experiment about this a while back, you should look up that thread. It's fascinating stuff.

[Deepbluediver]

In 3.5 there was an UA variant that did exactly this, so there's an official attempt at it if that's ever an issue. Most people thought that the piddling amounts of DR it offered wasn't worth the loss in AC that WotC implemented to compensate.

Personally I'm all for the idea and even tried to make my own version; I'll dig up the link if you want but it's, again, balanced toward 3.5. I'd kinda like to see someone take a stab at it for 5th edition but I'm still getting a handle on the power curve, so I couldn't really tell you if it's a good idea or not, particularly for higher levels.

The biggest issue as I understand it, is that balancing for DR is a lot harder than balancing for AC. Every extra point of AC is another -5% to hit, and To-Hit is most correlated with level or CR. Damage, on the other hand, tends to be much more varied by encounter, including types like magic-damage that DR from armor usually doesn't prevent. So DR tends to be much more effective against a scenario like Tucker's Kobolds or a fight against Drizzt than in a duel against the Tarrasque or Conan. This isn't an insurmountable problem, IMO; it's just the kind of thing that you should keep in mind when designing encounters and how the mechanics will interact with them.

Also, the more mechanics you have that stacking the smaller the sweet spot for balance can get. What I'm talking about is, Melee-types who tend to wear more armor also (on average) have more HP, and then you throw DR into that mix, you could end up in a place where any damage that is more than "piddling" to the tank will one-shot the wizard and the rogue. Again, not an insurmountable issue nor a completely impossible design philosophy (World of Warcraft builds its raids like this for example) but something to keep in mind depending on what kind of game you want.


Edit: I dug up the link: http://www.giantitp.com/forums/showthread.php?290667-Simplified-Improved-Armor
Again, this was for 3.5 not 5th edition, but maybe it will provide inspiration if you want to try and 'brew something of your won.

[Grod_The_Giant]

I spent a while (http://www.giantitp.com/forums/showthread.php?588922-5e-Variant-Armor-as-Temp-HP-%28no-longer-flat-reduction%29) working on it. I think I got something workable in the end, but it was a butt and a half and it's still not perfect. The final version is basically "armor gives you temp HP each round instead of increasing your AC." Trying to make it per-hit just did not work; DR that would help against a single-strong-attack monster or spell would utterly break multiple-small-attacks/attackers. Messing with how damage works in 5e is one of the hardest things you can do, in my experience. It's the core scaling mechanic in the game, and different characters and monsters interact with it in totally different ways. Messing around with something like Proficiency is easy by comparison.

[Deepbluediver]

I spent a while (http://www.giantitp.com/forums/showthread.php?588922-5e-Variant-Armor-as-Temp-HP-%28no-longer-flat-reduction%29) working on it. I think I got something workable in the end, but it was a butt and a half and it's still not perfect. The final version is basically "armor gives you temp HP each round instead of increasing your AC."
That's a thought I've had myself. In theory you could apply it to ANY form of DR, such as the Protection from Energy spell being per-round, but it would be a major change to the game's design and I was worried that players would reject it for not being very "realistic" (aka breaking verisimilitude).

[Zman]

Armor as DR is a great idea... just not for 5e or most RPGs for that matter. If you redesigned the entire damage paradigm and scaling you could implement it. But, with 5e as it stands you'll run into either being to little to be worth the reduction in AC, or too great you obsolete weak threats. And modifying an existing system for it to work well is a very tall order.

Years ago, I modified the official 3.5 variant back in the day to make it better, but even then it was far from perfect. If you're going to implement it in 5e, I'd probably increase the base armor calculation to 11+Dex, let armor give a reduced bonus to AC, ad a reasonable DR in the neighborhood of 1-8 depending on armor types. I'd also make Crits negate armor DR so weaker threats always pose some kind of threat. It'd be functional, but would still break down where higher damage attacks were concerned, but at lower levels it'd work like a charm, so for a more realistic E6 or E8 game, it'd be solid.


I'm actually working on an original D20 based system that uses a variant of Armor as DR. The system bounds more than just AC/Defense compared to 5e, namely it also bounds damage within an expected range. It also uses a WP/HP system with DR applying fully to most WP damage with a much smaller amount applying to HP damage. The particular configuration captures the feel of the relative impervious nature of Plate armor despite its easy of landing glancing blows. A crit bypassing a character's HP but getting soaked by there armor feels super really good and really hammers home the verisimilitude goal.

[Knaight]

Armor as DR works great in a lot of RPGs, but it's the sort of thing that tends to need to come fairly early in the design process. Retrofitting an armor as hit chance game to use it is generally less of a viable option unless there's some very serendipitous damage distribution mechanics. Retrofitting an armor as hit chance game that uses extensive HP/damage increase as the core of a dramatic leveling system which is built to use a minimally scaling hit chance system which includes armor is a mess at the best of times.

[LibraryOgre]

Borrow from Hackmaster, I would likely do something like this:

AC from Armor (and from Barbarian Constitution Bonus) would 1 for 1 be DR. Shields would be included.

AC from Dexterity (and from Monk Wisdom bonus) would be Defense. Sheilds would be included.

So, someone with a 12 Dexterity, in Leather Armor, with a shield, would have an AC/DR of 3 (1 point leather, 2 from armor), and an AC/Defense of 13 (10+1 dex + 2 shield).

I would also add that critical hits either double damage or ignore armor. Attacks which rely on saving throws generally ignore armor; attacks which rely on attack rolls generally are impacted by armor.

[Grod_The_Giant]

AC from Armor (and from Barbarian Constitution Bonus) would 1 for 1 be DR. Shields would be included.
The problem with stuff like this, I discovered, is that while every encounter of a given level should dish out a comperable amount of damage, the distribution of damage can vary wildly. A character in heavy armor might be virtually untouched by an encounter with a bunch of goblins, but get slaughtered by their ogre leader.

[Dienekes]

So Armor as DR has the problem that damage and attack doesn't really scale the same way in D&D, so swapping defense from making you harder to hit to dealing less damage is a bit of a problem.

To be rough about it. Every point of AC decreases the chance of being hit by 5%, therefore decreasing the total damage taken by 5% (ignoring criticals) over the course of an encounter. While every point of DR decreases damage taken by 1, Which can be anywhere from all the damage a creature can do if you're facing a housecat to 1/100th of the total damage dealt if you're facing a Tarrasque.

Grod's previously linked version is probably the best attempt I've seen to port Armor as DR into 5e. But you'll have more luck if you find a game in which health and damage scaling is not the focus of character power as it is in 5e. Different games like Riddle of Steel or Warhammer Fantasy have damage and health pretty much set and its your skills and capabilities that are the real improvements over the campaign. In that situation Armor as DR works much easier.

This tends to work better for games that are a bit more realistic and lower fantasy than D&D. Not that it can't work for a D&D style game, but you should know the inherent difficulties of implementing it.

[Zman]

To be rough about it. Every point of AC decreases the chance of being hit by 5%, therefore decreasing the total damage taken by 5% (ignoring criticals) over the course of an encounter. While every point of DR decreases damage taken by 1, Which can be anywhere from all the damage a creature can do if you're facing a housecat to 1/100th of the total damage dealt if you're facing a Tarrasque.

I generally agree with your post, but this is not correct. The absolute die percentage argument needs to go away. What matters is the relative change in expected damage taken by a point change in AC which exists in a range from approximately 5% to 50% and hangs closer to 10% as a median.

[LibraryOgre]

The problem with stuff like this, I discovered, is that while every encounter of a given level should dish out a comperable amount of damage, the distribution of damage can vary wildly. A character in heavy armor might be virtually untouched by an encounter with a bunch of goblins, but get slaughtered by their ogre leader.

And why shouldn't they be? I mean, they're only going to be unaffected by the goblins if the goblins don't have a way of dealing extra damage, and don't get any criticals... but why shouldn't someone in armor have little to fear from the scrubs, and everything to fear from the person built to break armor?

[Composer99]

The absolute die percentage argument needs to go away. What matters is the relative change in expected damage taken by a point change in AC which exists in a range from approximately 5% to 50% and hangs closer to 10% as a median.

Out of curiosity, why do you say that?

[Dienekes]

I generally agree with your post, but this is not correct. The absolute die percentage argument needs to go away. What matters is the relative change in expected damage taken by a point change in AC which exists in a range from approximately 5% to 50% and hangs closer to 10% as a median.

Yeah, now that you point that out, that's true. I'd still say that only furthers the point though that the 1 point of AC and the 1 point of DR scale at dramatically different rates.


And why shouldn't they be? I mean, they're only going to be unaffected by the goblins if the goblins don't have a way of dealing extra damage, and don't get any criticals... but why shouldn't someone in armor have little to fear from the scrubs, and everything to fear from the person built to break armor?

While this even has a drop of realism to it, since at armor's pinnacle knightly fighting very much was about crushing those who couldn't hurt you and engaging in combat with two-handed mass weapons as a means of beating other armored knights. There is a risk of really mess up the party balance if your tank's mechanics make it unable to effectively tank in any encounter that uses a high damage opponent. Which, at least for my games is pretty frequent.

[Grod_The_Giant]

And why shouldn't they be? I mean, they're only going to be unaffected by the goblins if the goblins don't have a way of dealing extra damage, and don't get any criticals... but why shouldn't someone in armor have little to fear from the scrubs, and everything to fear from the person built to break armor?
I mean, that's certainly a valid way of looking at it. The game as a whole wouldn't suffer too much, as long as the GM was careful... but they'd have to be careful, because replacing armor with soak isn't symmetrical. 5e right now doesn't distinguish between "foes that are hard to hit because they're agile" and "foes that are hard to hit because they're armored," but if you start using soak, the Monk is going to hit a brick wall when fighting that Helmed Horror, while being no more effective than they are now when fighting the ghost standing next to it. You'd have to add a second new rule to make lots-of-small-attacks more useful against lightly armored foes for balance. (Overwhelm penalties, maybe)

[Deepbluediver]

You'd have to add a second new rule to make lots-of-small-attacks more useful against lightly armored foes for balance. (Overwhelm penalties, maybe)
I never really considered it before, but if you made AC decrease over the course of a round on a per-hit basis, that would reward lots of fast-weak attacks and punish slow heavy hitters. For example, if your AC decreased by 1 every time someone attempted to attack you, and then reset at the end of your turn.

I don't know how you would sell that to players, but in theory I don't see anything unworkable about it from a purely mechanical perspective.

[Zman]

Out of curiosity, why do you say that?

Because the increase or decrease in change of hitting is 5%, ie needing a 11 vs an 10 is the different of hitting 50% of the time and 55% of the time, a 5% difference. But going from needing a 11 vs a 10 is actually a 10% increase in your chances of hitting and therefore a 10% increase in damage.


Yeah, now that you point that out, that's true. I'd still say that only furthers the point though that the 1 point of AC and the 1 point of DR scale at dramatically different rates.



While this even has a drop of realism to it, since at armor's pinnacle knightly fighting very much was about crushing those who couldn't hurt you and engaging in combat with two-handed mass weapons as a means of beating other armored knights. There is a risk of really mess up the party balance if your tank's mechanics make it unable to effectively tank in any encounter that uses a high damage opponent. Which, at least for my games is pretty frequent.

Oh, like I said, I agreed with the point of the post, but disagreed with the specific argument being put forward, specifically the 5% argument.

I completely agree about realism angle, the system I've been working on has done a solid job of capturing that verisimilitude while maintaining enough gameism to work. My way around it is by using a specific armor save, a d10 that is all or nothing save for applying armor's DR to Wound Point damage married to a much smaller damage reduction applied to all HP damage. So goblins with daggers will have ~70% of their attacks deflect right off plate armor, but have a chance to get around that armor. I also use crit effects for broad damage types, piercing weapons end up much better on the crit against armor, etc. In addition to the crit effect, they also bypass HP and go straight to WPs. Needless to say, everyone holds their breath for a split second when arrows are flying around, even a high level hero doesn't want to risk getting stuck with a lucky arrow. And when one comes up a 20, you can cut the tension with a knife as they roll their luck save to try and negate the critical. That may sound confusing, but instead of a bunch of static modifiers for things like cover, shields, and armor, the system uses multiple more simplified saves. Essentially characters always know what their to hit is and the AC is, very few things add static modifiers. The system also uses pretty extensive use of a Advantage/Disadvantage mechanic as well. As far as Armor goes it acts as a passive amount of resistance to HP damage in the range of 1-3 and is much more impactful when they roll an armor save to prevent Wound damage.

[LibraryOgre]

I never really considered it before, but if you made AC decrease over the course of a round on a per-hit basis, that would reward lots of fast-weak attacks and punish slow heavy hitters. For example, if your AC decreased by 1 every time someone attempted to attack you, and then reset at the end of your turn.

I don't know how you would sell that to players, but in theory I don't see anything unworkable about it from a purely mechanical perspective.

It would be another perk to two-weapon fighting.