D&D 5E Alternate AC calculation

What about changing the way AC is calculated and boosting shields?

AC = Base + Str + Dex + Prof/2
Shield AC = Str (max limit)
Unarmored AC: Base = 10

This makes Dexterity and Strength more balanced.
Your AC also scales as you level, becoming more proficient.
The heavier the armor you wear, the lower the benefit from Dexterity.
However, having great Strength improves your ability to use the best armor.
If you are not exerting energy wearing heavier armor, you are able to put more effort into defending with your shield.
If you have negative modifiers, your AC decreases accordingly.
To balance it more closely with the PHB numbers, you could either drop the half-proficiency addition, or you could subtract 1 from all base numbers, including unarmored.

Columns:
Armor type and name
Base AC
Max Strength mod added to Base AC
Max Dex mod added to Base AC
Max Str mod for Shield AC
Max AC with proficiency 2
Max AC with proficiency 6

Sweet idea. I'd hesitate on making the shield too useful though. How do you model plate armor making a shield obsolete though? If you model plate armor properly pretty much everyone has to use two handed smashing and piercing weapons to be effective against it, swords go bye bye and pole axes run the show.

Flexor the Mighty! said:

Sweet idea. I'd hesitate on making the shield too useful though. How do you model plate armor making a shield obsolete though? If you model plate armor properly pretty much everyone has to use two handed smashing and piercing weapons to be effective against it, swords go bye bye and pole axes run the show.

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The calcs above are way more than id want to do for a game, but i would say the easiest answer would be capping ac from armor at a number, for example if it was capped at 19, a plate user would only see 1 ac benefit from the standard shield but youd get the full benefit from lessor armor. Or if capped at 18 it could model plate armor obsoleting shields, which was effectively what happened.

However i think the idea of capping ac would be anathema to any min/maxers out there.

But otherwise modelling reality and d&d do not mix well - down that way lies madness...

It would be exceedingly complex, or just simply negate some builds enitrely (sorry messr scimitar, no dice!) And wotc have firmly decided to not go that route.

More realistically youd still add a dex to wearing heavy armour and the benefits to wearing plate in particular would be way stronger than a dextrous robe covered monk..

There is always Harnmaster for those who want realisim.

Joel Spanky Gray said:

I like your solution. Simple. But it doesn't quite succeed at the problem I was trying to solve. My problem is that I feel - again based on my own sparring and research - that shields are significantly undervalued. But in heavy armor, shields are not used as often and not as beneficial as to a lightly armored fighter. And weapons are good for defense too. I realize the calculation is a bit complex for DnD, but it makes shields more important for lightly armored fighters and less so for heavily armored ones.

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So modify Dausuul's draft. My attempt::

When you're hit by a melee attack, if you're wielding a melee weapon or a shield, you can use your reaction to deflect it. Make a DC 12 Dexterity check with proficiency. If you succeed, add +3 to your AC against that attack if your armor is light; +2 if it's medium; or +1 if it's heavy.

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My changes: I added the shield, and I made the effectiveness of the parry depend on the weight of the armor. This is an abstraction of several of the factors that apply to parrying while in armor. You could consider making the ability check either STR or DEX as I've had some outright clumsy and slow parries succeed against me due to how strong it was, but that may again be dragging too much detail into the abstraction.

Flexor the Mighty! said:

Sweet idea. I'd hesitate on making the shield too useful though. How do you model plate armor making a shield obsolete though? If you model plate armor properly pretty much everyone has to use two handed smashing and piercing weapons to be effective against it, swords go bye bye and pole axes run the show.

Click to expand...

Easiest way would be that most plate armour wearers take Heavy Armour Master feat, or that the very best suits of plate armour grant that same thing.
If you're going up against plate-wearers then, you really want to use a high-damage two-handed weapon in order to deal decent damage past the reduction. If you're wearing plate as well, (and thus are already hard to hit) the extra oomph is more important than the extra survivability of a shield.

The initially simplest, but most awkward method would probably be to uncap armour and Dex, and increase the AC of some armours. If the bog-standard warrior with a +3 or +4 to hit needs a 20 to hit you anyway, you don't really need a shield.
Needless to say, that approach may mess with bounded accuracy a lot however.

kirkspencer said:

My changes: I added the shield, and I made the effectiveness of the parry depend on the weight of the armor. This is an abstraction of several of the factors that apply to parrying while in armor. You could consider making the ability check either STR or DEX as I've had some outright clumsy and slow parries succeed against me due to how strong it was, but that may again be dragging too much detail into the abstraction.

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I'd make it a roll with the same bonus as their attack roll, or a Str check with proficiency using a shield, but the DC is their attack roll. Not only does this take a reaction, I might say that if they use a weapon to parry with, they make one less attack the next round, either from attack action or bonus action attack if they have one.
This makes the cost more severe when not using a shield, encouraging their use, but gives using an off-hand weapon a boost as well. It also makes the action more meaningful as a tactical decision rather than something that you do every round if you don't have anything else to do with your reaction.

You could simply remove the dex bonus to ac. Itd make the game more lethal, but perhaps that might appeal.

Certainly would make being armoured much more important, and gimp the rogue and monk somewhat (barbarian too, but his main defense really is resistance and tons of hp)

So a germ of honesty, I have no intention of changing it for my games. In my mind, the +2 for the shield is due to its use both for blocking and parrying. And the dex bonus to defense is to me as much using the parrying ability of weapons as much as it is footwork and ducking.

If i want detail and hours of modeling every little maneuver, there's Harnmaster (as Flexor noted) or Iron Crown. But I've come to prefer the semi-abstraction of the current system.

ro said:

What about changing the way AC is calculated and boosting shields?

AC = Base + Str + Dex + Prof/2
Shield AC = Str (max limit)
Unarmored AC: Base = 10

This makes Dexterity and Strength more balanced.
Your AC also scales as you level, becoming more proficient.
The heavier the armor you wear, the lower the benefit from Dexterity.
However, having great Strength improves your ability to use the best armor.
If you are not exerting energy wearing heavier armor, you are able to put more effort into defending with your shield.
If you have negative modifiers, your AC decreases accordingly.
To balance it more closely with the PHB numbers, you could either drop the half-proficiency addition, or you could subtract 1 from all base numbers, including unarmored.

Columns:
Armor type and name
Base AC
Max Strength mod added to Base AC
Max Dex mod added to Base AC
Max Str mod for Shield AC
Max AC with proficiency 2
Max AC with proficiency 6

Light	Base	Str Max	Dex Max	Shield Str Max	Max P=2	Max P=6
Padded	10	0	4	4	19	21
Leather	11	0	4	4	20	22
Studded Leather	12	0	4	4	21	23
Medium
Hide	11	0	3	3	18	20
Chain Shirt	11	0	3	3	18	20
Scale Mail	12	1	2	3	19	21
Breastplate	12	1	2	3	19	21
Half Plate	13	2	2	3	21	23
Heavy
Ring Mail	13	2	0	2	18	20
Chain Mail	13	3	0	2	19	21
Splint	13	4	0	2	20	22
Plate	13	5	0	2	21	23

Click to expand...

Also, this allows Medium Armor Master to be expanded to a simpler Armor Master:

Armor Master
- Increase your Dexterity or Strength score by 1, to a maximum of 20.
- Wearing armor doesn’t impose disadvantage on your Dexterity (Stealth) checks.
- When you wear armor, the maximum Dexterity bonus you can add increases by 1.