Stacking Impervious (weapon) with Impervious (armor)?


Rules Questions

Dark Archive

Hi guys!

I'm wondering if the following enchantments would stack for a spiked shield:

Impervious (weapon) +3,000gp wrote:
An impervious weapon is warded from damage and decay. A metallic weapon cannot rust and a wooden weapon cannot rot or warp, even by magical or supernatural means. An impervious weapon gains double the normal bonus to its hardness and hit points for each point of its enhancement bonus. The break DC for an impervious weapon and the wielder’s combat maneuver defense against sunder maneuvers against the impervious weapon each gain a bonus equal to twice the weapon’s enhancement bonus.
Impervious (armor or shield) +1 bonus wrote:
A shield or suit of armor with this special ability is especially hardy. It gains double its enhancement bonus to hardness and hit points (instead of just the enhancement bonus), its break DC increases by double its enhancement bonus, and it gains a bonus on saving throws against direct attacks (such as a rust monster’s rust ability) equal to its enhancement bonus.

Despite having the same name, one is designed to be used on weapons and the other on armor/shield, with distinct texts between them. As it happens, a spiked shield can be enchanted both as a weapon and as a shield.

So, if I make an adamantine large spiked shield (weapon part: +1 impervious)/(armor part: +1 impervious), would it have hardness 28 (20 + 4*1 + 4*1) and 60 hp (20 + 20*1 + 20*1)?

I'm making a character for a Wrath of the Righteous campaign and I'm intending to make this weapon a legendary weapon with the following ability:

Unyielding wrote:
A legendary item with this ability has double the hardness of a typical item of its type and triple the hit points. Furthermore, it’s immune to all attempts to sunder it made by non-mythic creatures. This is a persistent ability.

If the former is valid, would the unyielding double/triple only the basic hardness/hit points of the item or the modified by the enhancement bonus and magic abilities?

Would it be a) Hardness 56 [2*(20 + 4*1 +4*1)] and 180 hp [3*(20 + 20*1 + 20*1)] or b) Hardness 48 [2*20 + 4*1 +4*1] and 100 hp [3*20 + 20*1 + 20*1]?

Liberty's Edge

Pathfinder Companion Subscriber; Pathfinder Roleplaying Game Superscriber

For starter, all multipliers in Pathfinder are from the base value, so the adamantine shield would be hardness 28 and hp 60 if the bonus stack.

Second, the special quality isn't Impervious (weapon] and Impervious (armor or shield]. It is Impervious, full stop. You find it both in the weapon table and the armor/shield table, but it is the same ability, so you can't have two of them. On the other hand, as it is the same ability, it should affect and be affected by both the enhancements.

So an adamantine large spiked shield Unyielding, Impervious, weapon +1, shield+1 would be:
Hardness 20 (base), +2 (+1 weapon), +2 (+1 shield) = 24
if we add impervious +20 (double the hardness of the base item, not the enchanted item) = 44
hp 40 (base, it is adamantine, it has double the hp of steel), +20 (+1 weapon), +20 (+1 shield) = 80
if we add impervious +60 (x3 the hp of the base item, not the enchanted item) = 140

Sovereign Court

If you are just looking to increase the Hardness, look into Fortifying Stone, Reinforce Armaments, and Rags to Riches.

Dark Archive

Diego Rossi wrote:
Second, the special quality isn't Impervious (weapon] and Impervious (armor or shield]. It is Impervious, full stop. You find it both in the weapon table and the armor/shield table, but it is the same ability, so you can't have two of them. On the other hand, as it is the same ability, it should affect and be affected by both the enhancements.

I thought about it being the same ability, but I wasn't sure since they are not only listed in different tables, but are also described in two different places. Also, for a weapon it costs +3,000 gp while for an armor/shield it costs a +1 bonus.

If they are indeed the same and apply to both enchantments, it is really good news, for I'd be able to only pay 3,000gp as the +1 will become more and more expensive!

Diego Rossi wrote:

So an adamantine large spiked shield Unyielding, Impervious, weapon +1, shield+1 would be:

Hardness 20 (base), +2 (+1 weapon), +2 (+1 shield) = 24
if we add impervious +20 (double the hardness of the base item, not the enchanted item) = 44
hp 40 (base, it is adamantine, it has double the hp of steel), +20 (+1 weapon), +20 (+1 shield) = 80
if we add impervious +60 (x3 the hp of the base item, not the enchanted item) = 140

I believe now you mixed the names as effects in your calculations. A normal magic armor/shield/weapon gets +2 to its hardness and +10 hp for each +1 bonus on the item. The Impervious effect would double these, so +4 to hardness and +20 hp for each bonus.

So, an adamantine heavy shield impervious, weapon +1, shield +1 would be:

Hardness 20 (base), +4 (+1 weapon), +4 (+1 shield) = 28
Adding the Unyielding ability it would then double the base (20), for a total of 48.
hp 40 (base), +20 (+1 weapon), +20 (+1 shield) = 80
Adding the Unyielding ability it would then triple the base (40), for a total of 160

Also, can you point me to where in the rules it says and adamantine item has double the hp of a steel item? I know it has double the hardness, but the tables are weird and it appears it only increase hp from 30/in to 40/in so only a 30% increase instead of 100% (doubling).

Liberty's Edge

Pathfinder Companion Subscriber; Pathfinder Roleplaying Game Superscriber

My search-fu yesterday evidently was on a hiatus, so let's do it from scratch.

Ultimate equipment wrote:

Weapons and armor normally made of steel that are made of adamantine have one-third more hit points than normal.

Adamantine has 40 hit points per inch of thickness and hardness 20.

So 26 hp instead of 20.

Impervious really a different cost between weapons and armors. That is weird as the ability has the same name, and that would make it the same ability. As they have different prices that make different abilities.
But in any instance, I don't think they can stack, they will overlap. same name ability mean it is the same source. Until the name change, they are the same source.

Enchanting shield as weapons and shield as a defensive item are a mess. Reading again the different rules and some forum post, I think you should enchant them as a weapon and a shield separately, with the two sets of enhancements not affecting each other. But then you have the Bashing enhancement that is a defensive enhancement but gives an attack bonus effect.

As I have seen dragonbone spikes that can be applied to armor or shield as a reward in an AP, it seems that at least some author sees them as a separated weapon bolted on the shield.

At this point, there is no clear RAW answer. My only suggestion is to ask your GM.

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