Armor as DR

[SkipSandwich]

Good Day all!

One of my favorite hacks to d20 Modern was to apply some variant of "Armor as DR", and here is that same hack in new 5e flavor.

Armor as Damage Reduction
Instead of providing a bonus to AC, Armor reduces all damage taken by a flat amount, which is applied before applying any other forms of damage resistance, but cannot reduce damage to less than 1 point.

AC is now calculated as follows;
Unarmored/Light Armor: 8 + Proficiency bonus + Dexterity modifier
Medium Armor: 8 + Proficiency bonus + 1/2 Dexterity modifier
Heavy Armor: 8 + Proficiency bonus
When wearing armor you lack the proficiency for, you do not apply your proficiency bonus to AC.

Instead of adding Wis to AC, Monks apply double their proficiency bonus to AC when unarmored and not wearing a shield. Similarly, instead of applying Con to AC when unarmored, Barbarians gain Damage Reduction equal to their Con mod when unarmored.

To determine how much damage reduction a given suit of armor provides, take the AC bonus and subtract 10. Bonuses from magical armor are still applied to AC as normal. Creatures with natural armor bonuses to AC are unaffected, this only applies to worn armor. Shields are also unaffected, and increase AC as usual.

:EDIT: Yes, I am aware that under this change a 20th level monk has an AC as high as 25, but a 20th level sword-and-board fighter with a +3 Shield and +3 Plate had an AC of 26 under the original rules so that's not as crazy as it sounds. Currently the three runners for "Best Defense" under this change are;

Monk: max AC of 25 (8 + 12[prof] + 5[dex]), no Damage Reduction, only moderate base hp
Unarmored Barbarian: Max AC 19/21(8 + 6[prof] + 5[dex] +0/2[shield]) + DR 5[con], high base hp made effectively even higher by DR, high dex investment may require Str tradeoff.
Full Plate tank: Max AC 14/16(8+6[prof] + 0/2[shield]) + DR 8, Lower AC, but less stat dependent, higher DR offset by slightly lower base hp pool

[Mith]

Would the Barbarian DR stack with Rage Resistance? And would you keep Heavy Armour Master?

With Barbarians, they can get DR 7 with 24 CON. And the max AC was 24 any ways so the drop to 19 AC with resistance and DR 7 on top of a high HP pool is fine to my eyes.

[SkipSandwich]

Damage reduction from armor is applied before damage resistance (such as from rage) and cannot reduce damage to less than 1 point.

Heavy Armor Mastery is fine to leave as is, and is likely still a suboptimal choice of a feat.

[Mith]

I only ask about HAM because you have armour function as DR as the default.

[GalacticAxekick]

Armor as Damage Reduction
Instead of providing a bonus to AC, Armor reduces all damage taken by a flat amount, which is applied before applying any other forms of damage resistance, but cannot reduce damage to less than 1 point.Reasonable! One lesser concern is that armour shouldn't protect against some damage types (like Force and Psychic).

One greater concern is that DR disproportionately effects attackers that rely on multiple weak hits, since it gets to subtract damage from each hit. Martial classes and creatures who rely on Extra Attacks, Multiattack and Two-Weapon Fighting lag behind spellcasters, Paladin and Rogues who rely on burst damage. Make sure to compensate for this somehow.


AC is now calculated as follows;
Unarmored/Light Armor: 8 + Proficiency bonus + Dexterity modifier
Medium Armor: 8 + Proficiency bonus + 1/2 Dexterity modifier
Heavy Armor: 8 + Proficiency bonus
When wearing armor you lack the proficiency for, you do not apply your proficiency bonus to AC.

Instead of adding Wis to AC, Monks apply double their proficiency bonus to AC when unarmored and not wearing a shield. Similarly, instead of applying Con to AC when unarmored, Barbarians gain Damage Reduction equal to their Con mod when unarmored.

To determine how much damage reduction a given suit of armor provides, take the AC bonus and subtract 10. Bonuses from magical armor are still applied to AC as normal. Creatures with natural armor bonuses to AC are unaffected, this only applies to worn armor. Shields are also unaffected, and increase AC as usual.Less reasonable.

The highest AC you can normally get from light armour is 17. You raised this to 19 in addition to offering damage reduction.
The highest AC you can normally get from medium armour is also 17. You raised this to 17.5 in addition to offering damage reduction. Round it however.
The highest AC you can normally get from unarmoured defense is 20. You raised this to 25 but made it cost fewer ability score increases (in addition to offering the Barbarian damage reduction.
The highest AC you can normally get form heavy armour is 18. You dropped this to 14 after granting damage reduction.

This means light armour, medium armour and unarmoured defense are strictly improved while heavy armour gets the tradeoff and mage armour is unchanged. You've given Dex builds an enormous and unnecessary buff, especially the Monk and Barbarian.

Instead, everyone who gains DR should be losing AC. The more gain, the more loss. For instance:

Someone in light armour or no armour gets AC 10 + Dex. Instead of 11 AC, leather gives DR 1. Instead of 12 AC, studded leather gives DR 2. Tradeoff.
Someone in heavy armour gets AC 5 + Str. This low base AC and low potential are compensated by high DR (perhaps 3, 4 and 5 with improving armour). Tradeoff.
Unarmoured defense could offer DR equal to Wis or Con. Instead of increasing AC past that of light armour and beyond that of heavy armour, it would increase DR past that of light armour and towards that of heavy armour. Tradeoff.

This system means light armour is the easiest way to avoid burst damage (by avoiding attacks entirely) while heavy armour is the easiest way to avoid attrition (by weathering weak attacks indefinitely) and unarmoured defense gets the best of both (at the cost of requiring two ability scores rather than one). Tradeoff.

I'd probably remove medium armour as a concept


:EDIT: Yes, I am aware that under this change a 20th level monk has an AC as high as 25, but a 20th level sword-and-board fighter with a +3 Shield and +3 Plate had an AC of 26 under the original rules so that's not as crazy as it sounds. Currently the three runners for "Best Defense" under this change are;It's just as crazy as it sounds. "Sure I give 17th level Monks 25 AC for maxing Dex, but 20th level Fighters already get 26 AC by pumping Strength and using two Very Rare magic items" The Monk shouldn't have AC anywhere near that Fighter's unless they've got two magic items backing them up.

[SkipSandwich]

@Galactic AxeKick

You level some fair criticisms, I admit this was developed more for my 5e Modern port than for slotting directly into a normal game, so I did not give a ton of though to monk/barb that I probably should have.

How about the following?
Light/unarmored AC: 8 + Prof + Dex
Medium AC: 8 + 1/2 Prof + Dex
Heavy AC: 8 + Dex

Shields are +2 AC and allow you to the choice to use STR in place of DEX for AC calculations.

Unarmored Monks/Barbarians w/o shields Gain +2 AC and the ability to use WIS/CON respectively in place of DEX for AC Calculations. Effectively the perk is the same as having a shield while both hands remain free to wield weapons.

As far as Armor Reduction applying to all types of damage equally, that is deliberate since in my head it makes sense even for Psychic damage (wearing such heavy armor has a psycological buffing effect, allowing you to better resist mental attacks), but I prefer more cinenatic games where the PCs are larger-than-life action heroes. For a more down-to-earth kind of play, restricting to to physical damage types only would be perfectly fine.

As for ways of bypassing armor, you could consider it a form of active defense, which is lost whenever you would be denied your dex mod to AC, it would also make sense to be bypassed by critical hits and other forms of precision damage such as Sneak Attack.

[GalacticAxekick]

How about the following?
Light/unarmored AC: 8 + Prof + Dex
Medium AC: 8 + 1/2 Prof + Dex
Heavy AC: 8 + DexThis is almost exactly what you proposed earlier. My original criticism stands: "Light armour, medium armour and unarmoured defense are strictly improved while heavy armour gets the tradeoff and mage armour is unchanged. You've given Dex builds an enormous and unnecessary buff."

The one thing you changed is that Heavy AC relies on Dex instead of proficiency. This means it requires more ability score investment and caps at a lower number. Why would you nerf Heavy AC when it's already underpowered in your system?


Shields are +2 AC and allow you to the choice to use STR in place of DEX for AC calculations.So if I'm wearing heavy armour and want to use STR for AC calculations, I have to use a shield. No polearms. No heavy weapons. None of the tools that make STR builds advantageous.

It's a neat idea, but it doesn't fix the underlying issues: (a) light/medium/unarmored AC need to be nerfed in exchange for DR (b) Heavy AC shouldn't rely on DEX.


Unarmored Monks/Barbarians w/o shields Gain +2 AC and the ability to use WIS/CON respectively in place of DEX for AC Calculations. Effectively the perk is the same as having a shield while both hands remain free to wield weapons.This is a huge improvement over "double proficiency + Dex," since it doesn't offer as much free AC, but the underlying issue with unarmored AC being too high is still there. I can't stress enough that you need to lower it for this system to work.

[SkipSandwich]

It might be the case that the concept just does not work well outside the context of D20 Modern where ANY hit that deals damage equal to or greater than your CON score is potentially fatal if you fail your massive damage save. In vanilla Modern where AC is your only defense, this makes fights very swingy at all levels of play, which is what this house rule was originally created to address. Without that threat of death by massive damage, going all-in on AC bonuses carries no real risk.

[GalacticAxekick]

The concept of Armor as DR works perfectly fine in 5e. It isn't necessary, since there's no risk of massive damage to mitigate. But it's still interesting in theory and functional in practice.

My only criticism is that anyone who gains DR must lose AC in order to maintain balance.

[Rerem115]

You could have Heavy armor act more like it does in vanilla, and have the AC granted by the armor be just a flat number. That way, you could more easily tune things to match. That could also work for the armors of other weights. Heck, you could just keep the current system, but subtract I dunno, 2, maybe 3, from every armor's base AC (including natural and unarmored!) to account for the new damage reduction. That way, full plate+shield would offer AC 18 and DR 8, while a fully-kitted out Monk would have the same. Barbarians would still be kings, with a potential AC 22 and DR 12, but then again, that's assuming they reach level 20 and max Dex and Con before Strength while using a shield.

[GalacticAxekick]

That's a step in the right direction, since it trades AC for DR. It's nice that it's straightforward too.

But I personally think no armour should have both high AC and high DR. If so, we have two mechanics representing the same thing: deflection.

Since AC prevents hits, I would make it represent dodging. Normally a creature had 10 + Dex. A creature in heavy armour had 5 + Str + Dex.

Since DR softens hits, I would make it represent armour. Normally a creature has none. Increasingly durable armour and natural armour grants 1, 2, 3, etc.

A Monk's UD might give them extra AC equal to Wis when unarmoured.

A Barbarian's UD might give them DR equal to Con when unarmoured.

[SkipSandwich]

Part of the reason I want to link proficiency and Defense(AC) is that, all else being equal in terms of attributes and equipment, a more experienced character should be harder to hit.

Here's my latest itteration.
:EDIT: after some consideration and advice from a friend, I have modified all references to 1/2 of an attribute to simply be that attribued (max 2), as the freedom in saved attribute points is worth far more than 1 extra point of AC or AR.

Base AC equals 6+prof
Light/no armor adds full dex mod to AC
Medium adds dex (max 2)
Heavy adds nothing

Base Armor Reduction (DR) is 0, you increase it by wearing armor.
Light/no armor: 0~2 AR
Med armor: 2~4 AR + Con mod(max 2)
Heavy armor: 4~6 AR + Con mod


Light shields are + Str (max 2) to AC
Heavy shields are + Str (max 2) to AR

Unarmored and unshielded monks/barbarians add wis/con to AR (max 2) respectively.

At 20th we see the following maximums

Monk: AC 17, AR 2
Barb: AC 17, AR 2
Light armor fighter: AC 17, AR 2
+Light shield: AC 19, AR 2
+Heavy shield: AC 17, AR 4

Medium arnor: AC 14, AR 6
+Light shield: AC 16, AR 6
+Heavy shield: AC 14, AR 8

Heavy Armor: AC 12, AR 11
+Light shield: AC 14, AR 11
+Heavy shield: AC 12, AR 13

[Rerem115]

First off, what are light shields and heavy shields? That's not a mechanic that exists in 5e. Second, does armor only reduce BPS damage, or does it also reduce the elemental riders on some attacks? Third, barbarians get to use shields and still get their unarmored bonuses; I feel they should get to keep that. Also, are you doing this to everything in the MM, or just the PCs?

Overal, the system makes sense to me, and probably works just fine in the middle levels, but I can see some serious problems once you get to higher levels. AC becomes worth less as levels progress because monsters get progressively more likely to hit with level, so even high AC characters are more likely to be hit, skewing it in favor of DR.


Here are some calculations involving a fairly standard CR 17 monster, the Adult Red Dragon. It compares 2 Champion fighters, both with the Defense style and +1 AC from a magic item, but one in heavy armor and one in light, and assumes fire ignores DR.


AC
DR
Hit Chance
Damage
DPR


22
0
65%
15+15+26, 7 fire
36.4


21
0
70%
15+15+26, 7 fire
39.2


14
13
100%
15+15+26, 7 fire
17


21
2
70%
15+15+26, 7 fire
33.2


Granted, it doesn't account for critical hits, but those tend to favor DR, since that can mitigate part of the damage even if they do get hit.

As you can see, your proposed solution is a buff for armor users at high levels, and a significant buff for those who wear heavy armor. High level enemies simply don't miss, unless your players are rocking some serious magic items/know how to apply disadvantage/spam Shield or Cutting Words/some combination thereof. Unless you like to use enemies that have particularly nasty riders on their attacks, the fighter in full plate is going to be even tankier than before.

[SkipSandwich]

Light shields represent smaller, "parrying" shields, like the buckler and heavy shields represent more typical shields that cover most of the users upper body, such as scutum, viking shields and large kite shields.

By default, AR from non-magical sources protects against all forms of non-magical damage, and AR from magical sources (such as +1 Studded Leather) protects against even magical damage. But tweaking it to physical damage only will work just fine if that is your preference.

"Typeless" sources of damage (such as falling damage) bypass AR completely, as do critical hits. Like Defense, AR is considered "active" mitigation, and does not apply while you are helpless or restrained(such as against a foe that is grappling you), as your foe in those cases can easily damage you through the gaps at your joints.

[Rerem115]

I was more asking in order to figure out how to calculate its effects; there are some things, like dragonfire and the riders on the bite, using the Red Dragon again, that aren't explicitly magical, AFAIK. Also, how would DR work for cases where there are separate instances of damage; say you get hit by an arrow set alight by the spell Flame Arrow, and it does 4 piercing and 3 fire damage. Do you add those together, and then subtract your DR from the damage you take, or do you subtract your DR from each instance, assuming you have magical armor?

[SkipSandwich]

AR applies only once per attack. If you have an attack that deals 1d6 Bludgeoning + 3d4 thunder damage, add everything together then subtract AR from the total, to a minimum of 1 point of damage dealt. This is part of reasoning for having AR apply to all damage types equally.

Sneak attack and firebolt, which deal all thier damage in one lump sum are better at penetrating AR than Eldritch Blast and TWF which spread it over multiple attacks.