Question about Armor.

[Kyberwulf]

Why don't some armor stack? Is there a reason for this other then to screw over melee folk.

[Ravenica]

no bonus of the same type stacks, period. It affects everyone equally, more so to casters who "could" stack massive bonuses to everything without the limitation

[Slipperychicken]

The more "advanced" armors are already combinations of others. Fullplate, for example, is composed of plates over chain over padded leather.

All armor types give Armor bonuses. Bonuses of the same type don't stack, or else you would end up with stupid things like people wearing 7+ layers of Chain Shirts for the same price as Fullplate and getting crazy amounts of AC that way.

[Snowbluff]

There are few exceptions to bonuses that stack. Dastana, from OA, actually stack with some lighter armors. They don't stack with anything that already has gauntlets, though.

[Flickerdart]

All armor types give Armor bonuses. Bonuses of the same type don't stack, or else you would end up with stupid things like people wearing 7+ layers of Chain Shirts for the same price as Fullplate and getting crazy amounts of AC that way.
You couldn't do that anyway because you only have one armour item slot.

[KillianHawkeye]

You couldn't do that anyway because you only have one armour item slot.

Technically, item slots are only a limitation for magic items. There's really no rule (beyond common sense) as to how many things you can physically wear.

[TuggyNE]

It's not motivated by a desire to mess with mundanes' effectiveness, but it is a common-sensical sort of rule; realistically, it would be difficult to impossible to combine two types of armor (except, for the most part, for the combinations already provided, as noted), and that's not even considering more than two sets of armor at once.

In short: allowing suits of armor to stack with no special rules would lead to innumerable bizarre and silly results, special rules would have to be rather byzantine to be effective, and it really isn't very important to model that anyway.

Bonus Stacking Efficiency Tangent
For future reference, it's usually cost-effective to collect a number of bonuses of different types: e.g., +2 mithral chainmail (+2 enhancement armor bonus and +4 armor bonus = +6 armor bonus; +4 max Dex bonus and 18 Dex = +4 Dex bonus; 8150 gp), amulet of natural armor +2 (+2 enhancement natural armor bonus; 8000 gp), ring of protection +2 (+2 deflection bonus; 8000 gp), and let's say an animated heavy shield (minimum +1 enhancement shield bonus and +2 shield bonus = +3 shield bonus, doesn't require a hand to hold; 9170 gp) for a total of 27 AC and a cost of 33320. Compare the cost of +5 mithral chainmail and a +4 animated shield: 29150 gp + 36170 gp = 65320, or almost double the cost for the same AC.

[Jeff the Green]

Bonus Stacking Efficiency Tangent
For future reference, it's usually cost-effective to collect a number of bonuses of different types: e.g., +2 mithral chainmail (+2 enhancement armor bonus and +4 armor bonus = +6 armor bonus; +4 max Dex bonus and 18 Dex = +4 Dex bonus; 8150 gp), amulet of natural armor +2 (+2 enhancement natural armor bonus; 8000 gp), ring of protection +2 (+2 deflection bonus; 8000 gp), and let's say an animated heavy shield (minimum +1 enhancement shield bonus and +2 shield bonus = +3 shield bonus, doesn't require a hand to hold; 9170 gp) for a total of 27 AC and a cost of 33320. Compare the cost of +5 mithral chainmail and a +4 animated shield: 29150 gp + 36170 gp = 65320, or almost double the cost for the same AC.

Plus if you want to add a more interesting effect than +AC to your armor, the first option is even less expensive

[Uhtred]

But would a potion of Mage armor stack with a monk's wisdom bonus to AC?

[ThiagoMartell]

But would a potion of Mage armor stack with a monk's wisdom bonus to AC?

Yes, it would.

[TuggyNE]

But would a potion of Mage armor stack with a monk's wisdom bonus to AC?

A Monk's AC Bonus is effectively untyped, and stacks with everything except itself (and, arguably, identically-named features in other classes).

[Uhtred]

A Monk's AC Bonus is effectively untyped, and stacks with everything except itself (and, arguably, identically-named features in other classes).

So it would stack with bracers of armor, potion of Mage Armor, amulet of natural armor and the like, but if I had ninja levels my bonus wouldn't stack with the ninja's AC bonus?

[ThiagoMartell]

So it would stack with bracers of armor, potion of Mage Armor, amulet of natural armor and the like, but if I had ninja levels my bonus wouldn't stack with the ninja's AC bonus?

That's pretty much it, yeah

[Azoth]

A rare occassion of getting things to stack more than once would be Fist of the forest and Deepwarden's Con to AC. Fist of the Forest gives it similarly to a monk's wis to AC. Deepwarden allows you to replace your dex mod with your con mod to AC. Gottal love blocking attacks with your bare chest better than you could in full plate!

[TuggyNE]

So it would stack with bracers of armor, potion of Mage Armor...

Note that bracers of armor, potions of mage armor, and actual physical armor all have the same bonus type, and do not stack with each other.

There's actually a type of armor (Gnomish Twistcloth, Races of Stone?) that if you have proficiency, gives you a +1 armor bonus while counting you as unarmored for purposes of Monk etc. Handy, especially with magic vestments, although not necessarily worth a feat.