What order do AC bonuses apply?

[Quasqueton]

The thread about hitting cover got me thinking on this.

What AC bonuses apply to a character's AC first?

Say:

full plate = +8 AC
heavy shield = +2 AC
12 Dex = +1 AC
+3 ring of protection = +3 AC
Dodge feat = +1 AC

1. My group has always played it that the "movement" bonuses (like dodge and dexterity) apply first.

The above characters starts with AC 10. Then 11 including Dexterity. Then 12 including Dodge feat.

2. Then non-movement, non-armor bonuses apply.

The above character goes from AC 12 to AC 15 including the ring.

3. Then shield bonus.

The above character goes to AC 17 including the shield.

4. Then worn armor bonus.

The above character goes to AC 25 including the armor.


A Dex fighter with chain shirt (AC 18) might say of an attack that hits AC 13, "That didn't even hit my armor." Meaning the attack didn't make physical contact at all.

The "hitting cover" rules seems to imply that "movement" bonuses are applied last.

What order do you think of AC bonuses applying? Does it matter in the game mechanics?

Quasqueton

 

[reveal]

I've honestly never thought about it. I don't see why it would matter. Basically, the bonus to AC either applies or does not apply depending on the situation, a la Regular AC vs Touch AC vs Flat-footed AC. It just becomes a simple game of addition and subtraction at that point.

 

[Thanee]

I do it this way: touch AC is applied first, then shield, then armor. I use that to describe the attacks (i.e. dodged, parried with shield, deflected by armor, etc) in my PbP. Cover would be included in the touch AC, but applied last, that is, if an attack hits the original touch AC, but not the modified touch AC, then it hits the cover.

Bye
Thanee

 

[Jdvn1]

Nah, I don't think it matters. As a GM you could say a miss was "a glance off the armor" or you could say it was "a complete whiff"--it's just a matter of flavor.

 

[Sejs]

Generally I just break it down into two categories:

1) AC that keeps you from being hit at all, i.e. things that modify your Touch AC. (Dodge modifiers, dex mod, deflection, etc). We'll call this Avoidance AC.

2) AC that keeps you from being hurt when you get hit. (Armor bonus, natural armor bonus, shield bonus, etc). We'll call this Mitigation AC.

In those rare instances where you need an order of operation for AC then, apply the Avoidance first, then the Mitigation. Like so:

Example character has the following modifiers to their armor class~
A +5 armor bonus from wearing a Breastplate.
A +2 shield bonus from using a Heavy Wooden Shield.
A +1 natural armor bonus from an Amulet of Natural Armor +1
A +2 dexterity bonus from having a 14 dex.
A +2 deflection bonus from a Ring of Protection +2.

Total AC comes out to 22 (Touch AC 14): +8 in mitigation-type mods (armor, nat armor, shield) and a +4 in avoidance-type mods (dex, deflection).

An attacker that hits AC 0-14 fails to connect at all - the character dodged the attack. If the attacker hits AC 15-22, they're able to connect, but the character's tangible defenses prevent the attack from doing any harm - the strike skitters off an armor plate, is intercepted by their shield, and so forth.

 

[Patryn of Elvenshae]

The thread about hitting cover got me thinking on this.

...

What order do you think of AC bonuses applying? Does it matter in the game mechanics?

In terms of how I descibe combat, I consider the AC "levels" to be Base (incl. Size Mods), Touch, Touch + Shield, Full.

So, a modified roll of 9 means that a normal human (AC 10) doesn't even need to move out of the way - it's an incompetent series of blows.

A modified roll of 10 means the Dex 12 defender has managed to void all of the attacks.

A modified roll of 11 means the Dex 12, Light Shield-wielding defender has managed to void most of the attacks, and the ones he couldn't, he took on the shield.

Etc.

However, mechanically, it doesn't really matter in what order they are applied, in that the striking cover mechanics mention something like "would have hit except for Dodge / Etc. bonuses."

 

[Quasqueton]

So, a modified roll of 9 means that a normal human (AC 10) doesn't even need to move out of the way - it's an incompetent series of blows.

An inanimate object is treated as having Dex 0 (-5 AC), and the attacker gets +4 on the attack. So a human that didn't move to avoid an attack would be treated as [effectively] AC 1. A modified roll of 9 means the human *did* have to move some to avoid the attack. Even a human with Dex 8 would have moved, but just not as well as someone with average Dex, and so was struck by the attack.

However, mechanically, it doesn't really matter in what order they are applied, in that the striking cover mechanics mention something like "would have hit except for Dodge / Etc. bonuses."

That's what I meant with my question. This sounds like it assumes the dodging-type AC bonuses are at the top. Attack hitting AC 20 "would have hit if not for the dodge bonus bumping the AC up to 21."

Quasqueton

 

[Patryn of Elvenshae]

An inanimate object is treated as having Dex 0 (-5 AC), and the attacker gets +4 on the attack.

Did you read what I wrote? It's for descriptive purposes only. It doesn't have to be exact.

 

[kanithardm]

You have good ideas, but dont forget deflection bonuses.