D&D 5E AC and negative Dex modifier.

[Ragmon]

Quick question.

If I have -2 Dex modifier, then do I decrease my AC?

I'm just asking cause with heavy armor you don't receive +Dex mod but with medium or light you do.

And if I don't receive then in heavy why should I get it in medium or light?

 

[Syntallah]

From the PC Basic Rules (pg 44-45):

- If you wear light armor, you add your Dexterity modifier to the base number from your armor type to determine your Armor Class.
- If you wear medium armor, you add your Dexterity modifier, to a maximum of +2, to the base number from your armor type to determine your Armor Class.
- Heavy armor doesn’t let you add your Dexterity modifier to your Armor Class, but it also doesn’t penalize you if your Dexterity modifier is negative.

 

[The Crimson Binome]

And if I don't receive then in heavy why should I get it in medium or light?

One way to think of it is that Heavy armor has a maximum allowed Dexterity bonus of -5, and very high base AC. It looks kind of weird, but it's consistent mathematically.

You might have light armor that gives you (11 + Dex modifier, max Dex +5), or medium armor that gives you AC (14 + Dex modifier, max Dex +2), or heavy armor that gives you AC (22 + Dex modifier, max Dex -5).

 

[jrowland]

In case Syntallah wasn't clear: Yes you use your negative dex mod in light and medium. And no you don't in heavy.

 

[Ragmon]

So per RAW, negative modifier counts.

But how about as sensible ruling?

So I assume Dex represents moving around in combat, then the lack of Dex mod in heavy armor means the chracter doesent move around? If yes, why should the character receive the npenalty in M and L armor?

 

[Ravenheart87]

So I assume Dex represents moving around in combat, then the lack of Dex mod in heavy armor means the chracter doesent move around? If yes, why should the character receive the npenalty in M and L armor?

In case of heavy armor the lack of dexterity modifier means that most of your protection comes from the armor's ability to deflect and absorb blows and not from agility. The armor will protect you enough that your feeble dexterity won't count, but due to it's bulk your bonuses won't count either. Such abstraction happens if the system merges evasion, dodging, parrying and armor in a single Armor Class vlue.

 

[The Crimson Binome]

So I assume Dex represents moving around in combat, then the lack of Dex mod in heavy armor means the character doesn't move around? If yes, why should the character receive the penalty in M and L armor?

When you wear heavy armor, it weighs you down so much that your movement to dodge or parry is essentially a non-factor. When the ninja puts on plate armor, it slows her down to the point where she's no more evasive than the slowest brute with Dexterity 1 (and a modifier of -5).

 

[Paraxis]

It amazes me the hurdles people will jump to try and give a pure gamist design concept a simulationist excuse.

Heavy armor doesn't let a dexterity penalty hurt your AC so that fighters, paladins, and others heavy armor users can dump dex as a stat when they build their characters.

D&D is a mix of gamist design with nods to simulationist ideas spread around in it, trying to figure out things like AC, hit points, levels, and stuff and have them make sense outside of the game is almost a pointless task.

 

[Roger]

I think this sort of thing is a little bit less obvious than it could be due to the term "to hit", because the "to hit" roll is more than just making contact with the target with your weapon; it also includes the idea that you've hit the target well-enough to damage it.

Some versions of this game, and other games, go a bit farther with trying to model if, for example, your weapon hit the target's shield or his breastplate or whatever -- situations which in 5E would generally be 'misses'.

An entirely different layer of abstraction is in hit points, where it's not always entirely clear if hitting a guy with 200 hit points for 1 point of damage is actually some sort of physical contact or not.

So I think there's enough abstraction in the combat system to allow the sufficiently-motivated player to make just about any argument in terms of what's "sensible".

Or just ask the giant elk, assuming you can speak Giant Elk; he's got a pretty good grip on what's sensible around these parts.



Cheers,
Roger

 

[AverageCitizen]

So per RAW, negative modifier counts.But how about as sensible ruling? So I assume Dex represents moving around in combat, then the lack of Dex mod in heavy armor means the chracter doesent move around? If yes, why should the character receive the npenalty in M and L armor?

I think the thing is that light, medium, and no armor ACs assume a lot of your protection comes from your ability to move around. Heavy armor completely supplants that assumption with a flat AC. So yeah, heavily armored characters are not moving around in a defensive way.