D&D 5E Armor as Damage Reduction

[Dorian_Grey]

I've seen the idea posted about a few times but haven't stumbled across any hard and fast rules. I was thinking of implementing an armor as DR system in my next homebrew campaign. I have a few ideas but want to see what - if anything - others have done with 5th edition on this topic. My google-fu might have been weak as I didn't see anything. Saw stuff for 3rd and 4th edition, but not 5th.

In general I'm thinking that I'd keep the armor designations: light, medium, and heavy. I'd even keep Armor Class but it would be flat: AC 10 + Proficiency Bonus + Dex bonus. Primary melee characters could then add strength, constitution or double proficiency bonus. I'd let barbarians and monks, who are already supposed to get benefits from unarmored defense something more too.

Then you'd get DR of 2, 4, and 6 for light, medium, and heavy armor. Heavy armor might also offer resistance to a specific type of damage (i.e. plate vs slashing). Shields would add 1 DR and 1 AC.

As I said I'm just playing around with this right now. I'm not sure where I'm going to go with it.

 

[jasper]

How about this? Light DR 1, Medium DR 2, Heavy DR 3. No other changes.

 

[dave2008]

I've been using armor as DC with one of my groups since 4e. In 5e we currently use the AC-10 of the armor as DR. So plate is DR 8. Then add +1 DR for each magical +1 (nice bonus is magical armor doesn't break BA this way).

AC is unchanged, but you don't add (incorporate) armor to it, except as a penalty. -1 for light, -2 for medium, and -3 for heavy. Proficiency in the armor negates the penalty for light and medium and reduces heavy to a -1 penalty. It works for us.

 

[Blue]

Here's a few test cases to check against for a proposed Armor-as-DR system:

1. Weapon vs. caster PCs: Does expected damage vs. DR (after changes to hit and reduction) stay the same relative to magic damage?
1a. Remember, some spells target AC. Do they get reduced by the armor DR regardless of damage type?
2. Many small attacks: Does this make lots of little creatures either a lot more powerful or a lot weaker?
3. Few large attacks: Does this make creatures with a few big attacks like giants a lot more powerful or a lot weaker?
4. Many small vs. few large: How does a dual wielder end up vs. a greataxe users?
4a. Including criticals? (Twice as often vs. twice as big)
4b. How does this affect expected damage from the -5/+10 feats?

If the answer to any of those is true, then you're shifting the balance. I'd start by defining if and how you want to shift the balance first. Then design a system and test it out to see if it meets your goals.

 

[Blue]

A while ago I was playing with a system of armor as DR. I wanted to keep combat moving quickly so I didn't want to reduce expected damage per turn. My experience with Champions (now Hero System) was that everyone has defenses, it's relatively easy to hit, and defenses aren't enough to stop all of the damage even from weaker foes so a hit always meant something.

Basically I doubled all weapon damage, added proficiency to AC. Max dex stayed, but that just affected your AC. So heavy armor would mean no Dex to AC, medium armor would mean +2 max Dex to AC. Then I granted DR equal to what the armor would grant, with the limitation that it couldn't reduce it to less than 2 per tier of the foe. (So a bugbear is tier 1, converting CR to level. A hit will always do at least 2 HPs. A Vampire is CR 13, it will always do at least 6 HPs with a successful hit.)

I think spells that granted armor-like effects such as Mage Armor were instead DR. Monks got improved AC exactly like current but Barbarians Unarmed defense was Con as DR if unarmored. Really, I never did any math about how resistance and DR work out, it was quite powerful though.

Oh, spells that attacked AC were affected by DR. Something to offset that the AC they had to hit was lower. Though multi-hit spells like Eldritch Blast get boned.

Never ran the numbers, it could be way off.

 

[Jeff Carlsen]

Here's a few test cases to check against for a proposed Armor-as-DR system:

1. Weapon vs. caster PCs: Does expected damage vs. DR (after changes to hit and reduction) stay the same relative to magic damage?
1a. Remember, some spells target AC. Do they get reduced by the armor DR regardless of damage type?
2. Many small attacks: Does this make lots of little creatures either a lot more powerful or a lot weaker?
3. Few large attacks: Does this make creatures with a few big attacks like giants a lot more powerful or a lot weaker?
4. Many small vs. few large: How does a dual wielder end up vs. a greataxe users?
4a. Including criticals? (Twice as often vs. twice as big)
4b. How does this affect expected damage from the -5/+10 feats?

If the answer to any of those is true, then you're shifting the balance. I'd start by defining if and how you want to shift the balance first. Then design a system and test it out to see if it meets your goals.

These are good points, though I don't think you should start with defining your balance needs. The reason people like Armor as DR tends to be a verisimilitude thing, so it's more important that it meets the "feels right" goal.

That said, you'll probably want to account for the things above at some point, or at least be aware of them.

For example, for #1 and 1.a, you can say that Armor only provides damage reduction to effects that involve an attack roll.

Also, doesn't the DMG provide an optional rule for Armor as DR?

 

[Gadget]

I've seen many attempts over the years, but not many for 5e. I think Blue's questions warrant careful consideration. Usually you end up making the heavy armor wearer all but immune to small, light attackers like a group of goblins, especially if they still get some sort of bonus to traditional AC. Meanwhile, heavy hitters can hit more often and often blast through DR as the CR rises. This could seriously affect how Bounded Accuracy works in a game.

However, if you consider these dynamics and that is what the group wants and is okay with, then by all means, go ahead.

 

[Oofta]

There is already a feat that gives you DR (I don't have the book right handy) so you'll have to consider whether the DR stacks.

My personal preference is that I find DR really finicky and not worth the effort ... it's just an added layer of annoying math. So you might want to check with your players first.

The problem I see is some characters having virtual invulnerability to damage for certain types of creatures. Does it make sense that a heavily armored character could stand in the middle of a swarm of beetles and not take damage? What if they're dunked in a vat of acid? Others have already pointed out issues with spells.

If I was going to change the system I'd probably look at implementing armor as some type of temporary hit points. So a certain number of hits are going to bounce off the armor before getting through and causing real damage. Or maybe a combination of the ideas - heavy armor absorbs more of the hit but if you take a really hard hit (or a critical) some of the damage is "real" while some is just reflected as damage to the armor. Armor could be repaired over a long or short rest as you fit.

By doing that you could still whittle down your tanks with hordes of low level goblins if you want. Otherwise they might be able to ignore the horde, which doesn't seem very satisfying or in step with the spirit of 5E.

 

[dave2008]

Here's a few test cases to check against for a proposed Armor-as-DR system:

1. Weapon vs. caster PCs: Does expected damage vs. DR (after changes to hit and reduction) stay the same relative to magic damage?
1a. Remember, some spells target AC. Do they get reduced by the armor DR regardless of damage type?
2. Many small attacks: Does this make lots of little creatures either a lot more powerful or a lot weaker?
3. Few large attacks: Does this make creatures with a few big attacks like giants a lot more powerful or a lot weaker?
4. Many small vs. few large: How does a dual wielder end up vs. a greataxe users?
4a. Including criticals? (Twice as often vs. twice as big)
4b. How does this affect expected damage from the -5/+10 feats?

If the answer to any of those is true, then you're shifting the balance. I'd start by defining if and how you want to shift the balance first. Then design a system and test it out to see if it meets your goals.

These are only really relevant if you are designing a system for everyone. I find that in home games with people who trust each other these can all be resolved on the fly on a case by case basis.

 

[Edwin Suijkerbuijk]

A way i saw sombody do a version of damage reduction depending on armor was the following :

Leave the AC system as it is.
remove the damage bonus from ability scores from attacks.( also the magic bonus from magic weapons only apllies to your to hit bonus not damage)
if a target is hit add the amount by witch the AC was beated to the damage dealth.
atack rolls lower then the targets ac would still miss.

so a atack roll result of 19 would have a damage bonus of +9 against a AC 10 but only a +1 damage bonus against ac 18