Random thought: Constitution to AC?

[Segev]

This struck me as I read another thread where a post mentioned how 5e removing (essentially) flat footed AC makes it weird sometimes that your Dexterity makes you harder to hit even when you can't react effectively, such as when unconscious or blind to the incoming attack.

What if everybody by default added Constitution to AC instead of Dex, and adding Dex instead was a free action choice any time you are attacked and are able to respond effectively?

Complications include why Medium and Heavy armor cap or ignore Constitution to AC, and also tracking two different ACs if you regularly use Dexterity to AC.

I don't think this is worth it or really solves the "problem," but figured it might be of interest to discuss and brainstorm ways to improve on it or to approach solving the oddity of dex to unconscious/paralyzed AC.

If it is a problem at all. Maybe some of you have good ideas to justify the existing rules even in those odd cases! Please share them if so.

[Unoriginal]

This struck me as I read another thread where a post mentioned how 5e removing (essentially) flat footed AC makes it weird sometimes that your Dexterity makes you harder to hit even when you can't react effectively, such as when unconscious or blind to the incoming attack.

What if everybody by default added Constitution to AC instead of Dex, and adding Dex instead was a free action choice any time you are attacked and are able to respond effectively?

Complications include why Medium and Heavy armor cap or ignore Constitution to AC, and also tracking two different ACs if you regularly use Dexterity to AC.

I don't think this is worth it or really solves the "problem," but figured it might be of interest to discuss and brainstorm ways to improve on it or to approach solving the oddity of dex to unconscious/paralyzed AC.

If it is a problem at all. Maybe some of you have good ideas to justify the existing rules even in those odd cases! Please share them if so.

AC is an abstraction for how difficult it is to hit you. HPs are an abstraction for how much the hit impacts you if you're hit.

I don't think having the same stat for both in general is a good idea (exceptions like the Barbarian's Unarmored Defense or the Loxodon are fine, as they're exceptions fitting the specific fantastic themes of those concepts).

Also, "nimble but fragile" and "easy to hit but can rake it" are two concepts that I think deserve to exist in DnD.

That applies even if the target is caught flat-footed. Why should it be harder to hit a surprised ox than a surprised fox? Even when surprised, the fox is much more likely to react in a flash and twist/roll with the punch so it's not quite a hit compared to the big, sturdy ox.

[Pex]

DX to AC is fine as is, but I would support changing barbarian unarmored AC to 13 + CO modifier to make it easier to play the iconic loin-cloth warrior.

[MrStabby]

I am not sure of your specific implementation, but I think there is the essence of a good idea in your suggestion.

We have 6 saves (usually for spell type effects) including three mental saves. Multiple different avenues of attack for the mind hasn't really overcomplicated the system. I think mostly because everything is static - and symmetric. There are no different rules between saves (ok there are, things like rules for auto failing strength and dex saves sometimes). It's just another roll.

And having two different pre calculated ACs and the DM calling for one or the other would seem to add a huge amount of potential depth at the overall cost of not a lot of complexity.

[DomesticHausCat]

On one hand I'd be ok with making con added to ac instead of dex while immobile. But then again people would just choose to never move in combat if their con was very high. It could work if you're unconscious though.

[noob]

This struck me as I read another thread where a post mentioned how 5e removing (essentially) flat footed AC makes it weird sometimes that your Dexterity makes you harder to hit even when you can't react effectively, such as when unconscious or blind to the incoming attack.

What if everybody by default added Constitution to AC instead of Dex, and adding Dex instead was a free action choice any time you are attacked and are able to respond effectively?

Complications include why Medium and Heavy armor cap or ignore Constitution to AC, and also tracking two different ACs if you regularly use Dexterity to AC.

I don't think this is worth it or really solves the "problem," but figured it might be of interest to discuss and brainstorm ways to improve on it or to approach solving the oddity of dex to unconscious/paralyzed AC.

If it is a problem at all. Maybe some of you have good ideas to justify the existing rules even in those odd cases! Please share them if so.

Does it means barbarians would get something else to replace unarmoured defence?

[strangebloke]

ultimately fluff aside the mechanics are what determines what constitution 'is'. DEX is what lets you dodge, CON is what lets you take a hit. You could just as easily have a system where CON is what makes it hard to damage you, and you have some fixed number of "dodge points" or "luck points" that you can use to avoid dying if an attack surpasses your damage threshold.

In other words its all arbitrary and you can do whatever you want.

[werescythe]

DX to AC is fine as is, but I would support changing barbarian unarmored AC to 13 + CO modifier to make it easier to play the iconic loin-cloth warrior.

Personally I don't mind Barbs the way they are. What I think would be interesting (and cool for barbs) is if your AC used either your Dex or Con (whichever is higher) when it applies (because some armors don't add dex and therefore shouldn't add con either to the AC) but Barbs get to add not one but both.

[Segev]

Does it means barbarians would get something else to replace unarmoured defence?

I think I'd have it just be they get both, rather than "either."

[Sigreid]

I think I personally would rather have the con modifier be damage reduction rather than hp per level. But I know that won't happen.

For your idea, I don't see the harm in it.

[MutantDragon]

This struck me as I read another thread where a post mentioned how 5e removing (essentially) flat footed AC makes it weird sometimes that your Dexterity makes you harder to hit even when you can't react effectively, such as when unconscious or blind to the incoming attack.

What if everybody by default added Constitution to AC instead of Dex, and adding Dex instead was a free action choice any time you are attacked and are able to respond effectively?

Complications include why Medium and Heavy armor cap or ignore Constitution to AC, and also tracking two different ACs if you regularly use Dexterity to AC.

I don't think this is worth it or really solves the "problem," but figured it might be of interest to discuss and brainstorm ways to improve on it or to approach solving the oddity of dex to unconscious/paralyzed AC.

If it is a problem at all. Maybe some of you have good ideas to justify the existing rules even in those odd cases! Please share them if so.

Here's my thoughts on this. Firstly, as you said, this doesn't solve the issue. It just changes the flavor so swords are bouncing off of people instead of people evading the swords. So, let's ask ourselves what the problem is. Dexterity applies to people's defenses when it otherwise would make no sense. Ok, so, rather than complicating things with Constitution, let's just focus on that. The simple and logical rule to fix the issue is to just not apply any positive Dexterity modifiers to AC when incapacitated/immobilized/anything else that renders them unable to dodge.

[Damon_Tor]

AC is an abstraction for how difficult it is to hit you. HPs are an abstraction for how much the hit impacts you if you're hit.

I don't think having the same stat for both in general is a good idea (exceptions like the Barbarian's Unarmored Defense or the Loxodon are fine, as they're exceptions fitting the specific fantastic themes of those concepts).

The two things are far more muddled than you're giving them credit for. AC includes but is not limited to the difficulty in hitting a target, but it also includes the difficulty of damaging the target in a meaningful way. The broad side of a barn, quite literally, has an AC. All objects do. That's not because it's hard to hit the broad side of a barn, but because there is a non-zero chance that my attack will do nothing of consequence to it.

[Unoriginal]

The two things are far more muddled than you're giving them credit for. AC includes but is not limited to the difficulty in hitting a target, but it also includes the difficulty of damaging the target in a meaningful way. The broad side of a barn, quite literally, has an AC. All objects do. That's not because it's hard to hit the broad side of a barn, but because there is a non-zero chance that my attack will do nothing of consequence to it.

More than fair point.

Would "AC is the abstraction for how hard it is to meaningfuly hit something, HP is the abstraction for how meaningfuly something is hit" be better?

[DomesticHausCat]

I think I personally would rather have the con modifier be damage reduction rather than hp per level. But I know that won't happen.

For your idea, I don't see the harm in it.

That sort of happens already due to hp increase.

[Damon_Tor]

More than fair point.

Would "AC is the abstraction for how hard it is to meaningfuly hit something, HP is the abstraction for how meaningfuly something is hit" be better?

Quibble: AC is the abstraction for how how hard it is to meaningfully hit something, HP is an abstraction to track the quantity of meaningful hits that thing can take. The abstraction for HOW meaningful is damage.

[Amechra]

Clearly the solution is to scrap AC entirely. Instead, attacks cause the target to make a Dex save vs. your attack DC, with success negating the damage. Barbarians can make Con saves instead, Monks can make Wis saves instead, shields let you make Strength saves instead, and armor is damage reduction.

This is the best solution to the problem of incapacitated people getting Dex to AC, since incapacitated people automatically fail Dexterity saves. It will cause no problems and I will be taking no questions, please and thank you.

[Sigreid]

That sort of happens already due to hp increase.

Con Mod as damage reduction would have a much greater impact than the HP. I realize that.

[strangebloke]

Quibble: AC is the abstraction for how how hard it is to meaningfully hit something, HP is an abstraction to track the quantity of meaningful hits that thing can take. The abstraction for HOW meaningful is damage.

It is, all of it, entirely abstract. There is nothing at any point in this system that correlates to anything real.

Armor Class does not refer to armor, or to class, or to anything. It's an arbitrary measure of 'toughness' except that toughness is something else, and AC also encapsulates active defenses like shields and the shield spell and 'being quick enough to move out of the way' but NOT other active features like the 'dodge' action (which is separate from your standard ability to apply DEX to AC) but it does cover things like 'tough hide' except that things that have tough hides like crocodiles have AC 12 which is on par with, uh, a swan?

And needless to say that HP is even more inconsistent. Is it meat? If so does that mean that a pair of high level champions are just eviscerating each other for 30-40 seconds until one finally passes out after 40 maul strikes to the face? But it is meat when it comes to giant creatures, right? Or maybe not? But if it isn't meat, then what is healing, and why does it work the same whether it is or is not meat.

It's all completely arbitrary. The Mechanics Come First. "How any of this works" is left as an exercise to the DM. Figure out how you want to narrate the high level champion battle yourself - the mechanics don't care.