Thoughts on Proficiency and AC

[jmucchiello]

I've been nagged by a minor inconsistency in 5E. (Just one? for the purposes of this thread, yes, just one. Well, maybe two.)

When you calculate the DC of just about everything in 5E, you add 8 + ability mod + proficiency bonus, if proficient. But when you calculate Armor Class, you add armor value + (possibly limited) dexterity bonus + shield value. So what happens if you use proficiency bonus with armor:

Armor
[table="align:left"][tr][td]Armor Type
Light
Padded
Leather
Studded Leather
Medium
Hide
Chainshirt
Scale Mail
Breastplate
Half Plate
Heavy
Ring Mail
Chain Mail
Splint
Plate[/td][td="align:center"]Bonus

+1
+1
+2

+2
+3
+4
+4
+5

+4
+6
+7
+8[/td][td="align:center"]Max Dex Bonus

no limit
no limit
no limit

+2
+2
+2
+2
+2

+0
+0
+0
+0[/td][td="align:center"]Min Str to use

-
-
-

-
-
-
-
-

-
13
15
15[/td][/tr][/table]

So a first level paladin in Chain Mail would have a AC 16 (8 + 6 + 2 + 0). At 5th level it would become AC 17 (8 + 6 + 3 + 0). At 19th level AC 20 (8 + 6 + 6 + 0).

Shield proficiency does not add proficiency bonus.

Can Rogues and Bards become Expert with their Armor? Probably a bit OP. But imagine the 19th level rogue in Leather armor and 20 Dex having a 26 AC (8 + 1 + 12 + 5). In a serious game, I would not allow this. But in a fun game, why not?

Might need to give a few pluses to the existing higher level monsters to compensate. And I know the system is supposed to avoid that kind of chasing the mean. But I like the idea of characters getting better at using their armor to their advantage.

 

[TwoSix]

So instead of 10 + armor + dex + shield, it's 8 + prof + armor + dex + shield?

Hmm, that's not bad.

 

[dave2008]

Might need to give a few pluses to the existing higher level monsters to compensate. And I know the system is supposed to avoid that kind of chasing the mean. But I like the idea of characters getting better at using their armor to their advantage.

Why not just add prof. bonus to monsters too? They generally use the same system as PCs now.

 

[The Crimson Binome]

It makes sense to me. The only problem is that PCs are already ludicrously durable, and increasing their ACs at high levels would make them more-so. I would prefer to address that by reducing HP to compensate, but there are any number of approaches you could take.

 

[jgsugden]

You're just raising PC ACs with this system at levels 5 to 20. The impact will be minor at 5 to 8. From 9 to 12 you'll feel it a bit more, but it won't be overwhelming. 13 to 16 will be noticeable for sure. At 17th level it is a +4 bonus. That changes a lot of the assumptions of the game at these high levels...

However, as many games don't really extend far beyond 13th level, it is not really that big of a deal.

All that being said, it would not interest me. The game is built on the assumption of flatter ACs at higher levels, so I prefer to keep within that expectation.

 

[dwelwell]

I like the idea. It provides a place for skill and expertise in defense, a concept sorely lacking in 5e. It also means you can be skill without having a high DEX, which is nice.

 

[cbwjm]

I like this, it does add some additional calculations to the game but that shouldn't be too much of a problem once the AC is worked out and play begins. None of the scores below include +2 for a shield.

With a maximum dexterity bonus (+5 for light armour, +2 for medium armour), both the best light armour and medium armour come out with a final AC of 21 at level 17 and heavy armour an AC of 22.

A wizard with mage armour is going to have an easier time of it. If they have a dexterity of 14 their whole career they have an AC range of 15 to 19 with mage armour up instead of a flat score of 15.

If monks and barbarians are to be considered proficient with unarmoured defence, they can end up with scores quite high. Starting score for a monk would often be 16 (8 +2 Prof. +3 Dex. +3 Wis) which is pretty standard, but at level 17 if the dexterity and wisdom scores are maxed they end up with 24 (8 +6 +5 +5). I guess that keeps the monk comparable with the magical bonuses for armour that others might get. Barbarians might be slightly less as they will be focusing on strength rather than dexterity in most cases, though they can use a shield as well.

This also gives a regular person with no armour, no Dexterity bonus an ascending AC from 10 to 14 (assuming that, like unarmed strikes, everyone is proficient in defending themselves) which I like a better than just 10 + dexterity.

 

[Bardbarian]

Why not just remove proficiency bonus all together? Adding Proficiency to defense makes the numbers meaningless. at level 5 I get a +1 to hit and you get +1 defense then what's the point we hit on the same number as last level. Defense is not supposed to scale with level, 5th edition uses HP as the defensive scaling factor.

 

[cbwjm]

Probably because the party members aren't generally fighting each other? Those low level orcs will have the same +2 proficiency modifier when the party has a +3 modifier. Against opponents with the same proficiency bonus the bonuses do cancel out, but the whole world doesn't move along at the same pace as the PCs.

 

[The Crimson Binome]

Why not just remove proficiency bonus all together? Adding Proficiency to defense makes the numbers meaningless. at level 5 I get a +1 to hit and you get +1 defense then what's the point we hit on the same number as last level.

That would only be true in the specific case that you are fighting an enemy that's roughly the same level as you are. If you're fighting a stronger or weaker enemy, then the difference would become much more apparent.