What kind of armor bonuses/effects stack?

[eyebreaker7]

"Armor Bonus
An armor bonus applies to Armor Class and is granted by armor or by a spell or magical effect that mimics armor. Armor bonuses stack with all other bonuses to Armor Class (even with natural armor bonuses) except other armor bonuses. An armor bonus doesn't apply against touch attacks, except for armor bonuses granted by force effects (such as the mage armor spell) which apply against incorporeal touch attacks, such as that of a shadow."

What exactly does that mean? Do they stack or not?

Natural armor
amulet of natural armor
bracers of armor
mage armor spell
cloak of protection
ring of protection
robe of the archmagi
vest of the archmagi
anything I forgot

what out of those will stack with natural armor?
This is for a mage/sorcerer obviously.

[Evoker]

The rule of thumb is that an "armor" bonus is a bonus to AC, and behaves in the same way that a "deflection" or "shield" bonus does: only one bonus of the same name. Armor (the items) provides an "armor" bonus to your AC (armor class). Mage armor (the spell) provides an "armor" bonus to AC, and doesn't stack with other "armor" bonuses, including those from the items usually termed Armor. An Amulet of Natural Armor, on the other hand provides a "natural armor" bonus (Technically, it provides an enchantment bonus to your natural armor, but for the sake of argument let's assume you don't have natural armor from some other source) to AC. Thus, it stacks with an "armor" bonus. Apply the same rule of thumb to any bonus you come across: Bonuses with the same name don't stack, bonuses without a name (so-called "untyped" bonuses) always stack.

[Kayblis]

Armor bonus is one of the many bonus types that add to AC. They stack with any other bonus type, but as usual, not with itself. This means:

Natural Armor stacks with Armor bonus, as well as with the amulet of natural armor because that's an enhancement bonus to natural armor.
Armor bonus doesn't stack with itself, so the mage armor spell, bracers of armor, robe of the archmagi and vest of the archmagi don't stack between themselves. Only the highest bonus between these works. These also don't stack with normal armor.
Ring of protection offers a Deflection bonus and stacks with all the above.
The Shield spell provides a Shield bonus and stacks with all the above.

[the_tick_rules]

bonuses of the same type do not stack. you cannot wear two chain shirts (4 armor) and get a combined 8 armor class bonus because they are both armor. bracers of armor grant an armor bonus so you cannot get 12 ac boost by wearing bracers +8 and a chain shirt. an amulet of natural armor does stack with armor because natural armor and armor are two different types. I don't know what of bonus everything on that list grants but for example rings would stack because they grant a deflection type bonus. but you could not wear two rings of protection +5 and get a +10. Oh and dodge bonuses to ac stack they are the only consistent exception.

[eyebreaker7]

So if I understand correctly you can wear:

robe/vest of the archmagi
amulet of natural armor
ring of protection
and also benefit from natural armor?

[Evoker]

So if I understand correctly you can wear:

robe/vest of the archmagi
amulet of natural armor
ring of protection
and also benefit from natural armor?

Yup. There's probably a few more types you can use to boost your AC. A dusty rose Ioun stone will set you back only 5000 gp for a no-slot +1 insight bonus.

[eyebreaker7]

I forgot the shield spell also?
What about Protection from evil/good/law/chaos spells?

[Evoker]

I forgot the shield spell also?
What about Protection from evil/good/law/chaos spells?
Shield spell provides a shield bonus, and stacks.
Protection from E/G/L/C is a deflection bonus, and as such does not stack with the ring of protection, as that also provides a deflection bonus.

[eyebreaker7]

Ok I'm pretty sure I got it now :)
Thanks everyone :)

[Gruftzwerg]

to sum it all up and clear a few special chases:

- "untyped bonuses" always stack to AC

- Dodge Bonus is the sole (general) exception that stacks with itself. So you can stack as much Dodge bonuses as you want (note that some 3.5 bases PC games have a cap of +15 here, but in regular pen & paper 3.5 this does not exist).

- For every other AC increasing category only the strongest source applies and the categories only stack with each other (but not with their own category).

There are 3 base AC increasing categories:
1. Armor bonus (regular armor, Mage Armor, Bracers of Armor ...)
2. Shield bonus (regular shield, Shield (spell), ...)
3. Natural Armor bonus (natural "Natural Armor bonus", spells (mostly polymorph spells) that give you a set "Natural Armor bonus" without any specific kind/type mentioned.
(again they stack with each other but not with themselves !)


Each of these base categories can further have their own set of different enhancement types. This means, you can have a certain type stacking once for every category (e.g enchantment bonus to Armor, Shield and Natural Armor). I'll mention the most common (imho):


- enchantment bonus is the most common source and thus it can happen sometimes that you have 2 or more sources overlapping each other.
- celestial bonus is another type that is somewhat common for armor. But IIRC this seems to be an exclusive type for armor, since I'm not aware of any celestial shield or natural armor bonuses right of the bat. (maybe someone else can help us out here^^).
- luck bonus (same as celestial, don't know if any luck bonuses exist for shields and natural armor)
...

On base of the given info I would further like to point out the special case Bracers of Armor:
Since the bracers give "armor bonus" (like regular armor) and can be enhanced like armor, you can add up to +5 "enchantment bonus to armor" for a max possible AC increase of 13.
Bracers of Armor +8 +5(enchantment bonus) = +13 AC

edit: cleared up some passages that might be misleading..^^

[Khedrac]

edit: cleared up some passages that might be misleading..^^
And you still made a mess of it - sorry.

Trying to re-clarify.

In general there are a number of different types of bonus to anything, for Armor Class the main ones are:
Untyped
Armor
Natural Armor
Deflection
Shield
Dodge
Dexterity
Notably, one a lot of people think is a bonus type is not, and that is enhancement - it is impossible (afaik) to get an enhancement bonus to AC.
Instead, you can get enhancement bonuses to your different types of AC.
A good example of this is the amulet of natural armor which provides an enhancement bonus to natural armor. This means it will stack with things that grant natural armor, but not with things that grant other enhancements to natural armor like the spell barkskin.

Bonus stacking rules are complex, but only apply to bonuses of the same type - bonuses of different types always stack (barring specific rules to the contrary).
Skip Williams' article on bonus stacking it is very good if someone can link it.
One general rules applies - a bonus never stacks with itself, so if a spell gives you an untyped bonus to AC then two castings of the spell don't stack - it's the same bonus and doesn't stack with itself.
For AC most bonuses do not stack (so use the highest applicable of that type), but Dodge and Untyped and specific exceptions to this rule and will stack (barring same source).

For items and enhancement bonuses, the enhancement bonus only applies to the item it is on, so if you are wearing leather (armor bonus of 2) that has an enhancement bonus of 3 and someone casts mage armor on you (armor bonus 4), you cannot apply the +3 enhancement to the mage armor to get 7, it is the leather that is enhanced to 5 so you use the 5 (being bigger than 4).

[tyckspoon]

Notably, one a lot of people think is a bonus type is not, and that is enhancement - it is impossible (afaik) to get an enhancement bonus to AC.

There is at least one enhancement bonus direct to AC somewhere, although I'd have to do a fair bit of digging to find it. The thing (..I think it's an item?) that does it was probably an editing/errata oversight, but as far as I know it was not officially corrected, so stands as RAW.

[Psyren]

Enhancement doesn't usually boost AC directly, but it can be applied to one of the existing types. An amulet of natural armor for instance provides an enhancement bonus to natural armor, which would in turn stack with a natural armor bonus a creature gets somewhere else (e.g. from their race.)

For example, if you put an amulet of natural armor +2 on a lizardfolk, his total natural armor bonus would be +7 (+5 racial natural armor bonus, +2 enhancement bonus to his natural armor from the amulet.) But if he then drank a potion of barkskin, his AC wouldn't change, because barkskin provides a +2 enhancement bonus to natural armor (same as the amulet) and they don't stack - he would still be at +7 after drinking the potion.

...And writing all of that out, I'm starting to understand why some of my friends switched to 5e and never looked back...

[MaxiDuRaritry]

There are two exceptions to the "armor bonuses to AC do not stack with other armor bonuses" paradigm that I'm aware of in 3e: the dastana bracers (from the Arms & Equipment Guide and Oriental Adventures) and the chahar-aina (Oriental Adventures). They explicitly provide armor bonuses to AC and stack with other armor bonuses to AC. They also have their own very specific rules and exceptions for how they function.

More details can be found here (http://minmaxforum.com/index.php?topic=11739.0).

Of course, there are times when you'll want to utilize multiple armor bonuses that don't stack. For instance, a psion wearing +1 mithral chain shirt armor with a bunch of armor abilities and a manifestation of inertial armor. The actual armor grants special armor abilities (and possibly mundane armor things like armor spikes), as well as a source of armor bonus if the psion's buffs get dispelled, while the inertial armor potentially grants a much larger armor bonus, and it works against attacks from incorporeal sources.

Also, there is no such thing as an "enchantment" bonus. Enhancement, yes, but not enchantment. Enchantment is a class of spell that is generally mind-affecting, which are mental effects that affect creatures. Note that you also cannot "enchant" an item, as objects are immune to mind-affecting effects.

[eyebreaker7]

Going back over stuff and want to make sure about a couple things:

Natural armor = natural armor
armor worn (studded leather +3 for example) OR bracers of armor +6 = armor bonus (magical +3 armor or +6 bracers for example)
amulet of natural armor = enhancement
ring of protection = deflection bonus
shield spell (or ring of force shield) = shield bonus
dodge bonuses to ac DO stack they are the only consistent exception.
dusty rose Ioun stone = +1 insight bonus

all of that works together?

How about potions? Working together with no other magical items, just natural armor, Dex, dodge and anything else I'm forgetting please let me know.

Barkskin = enhancement bonus to the creature’s existing natural armor bonus
Mage Armor = armor bonus
Shield of Faith = deflection bonus
Shield ??? = shield bonus. Can this potion be made? According to the rules it can as far as I can tell but it's not on the potion/oil listings

Obviously there's also the potion of cat's grace that would help with a Dex modifier.

[Zanos]

There is at least one enhancement bonus direct to AC somewhere, although I'd have to do a fair bit of digging to find it. The thing (..I think it's an item?) that does it was probably an editing/errata oversight, but as far as I know it was not officially corrected, so stands as RAW.
https://www.d20srd.org/srd/psionic/powers/thickenSkin.htm

Does seem like an editing mistake, but there ya go.

[Necroticplague]

https://www.d20srd.org/srd/psionic/powers/thickenSkin.htm

Does seem like an editing mistake, but there ya go.


There is at least one enhancement bonus direct to AC somewhere, although I'd have to do a fair bit of digging to find it. The thing (..I think it's an item?) that does it was probably an editing/errata oversight, but as far as I know it was not officially corrected, so stands as RAW.

There's also the good ol' Item Alteration infusion, which can make anything giving a non-prafane/sacred bonus to AC give an enhancement bonus to AC.

And still wondering WTF they were thinking when they wrote that, because the only three ways I can envision is working out are abusively ('I'm going stack up to epic skill check levels way before then, thanks dodge bonuses to escape artist stacking'), bafflingly (for those with a poor grasp of stacking, it doesn't appear to do anything), or uselessely (since you normally will try to avoid having items that don't stack anyway, so it's unlikely to be of any significant use).

[truemane]

Metamagic Mod: days between posts also stack. Thread closed.