The Ironskin spell states as follows (emphasis mine):

You gain a +4 enhancement bonus to your existing natural armor bonus (if you do not have a natural armor bonus, you are considered to have an effective natural armor bonus of +0). This enhancement bonus increases by 1 for every 4 caster levels above 4th, to a maximum of +7 at 15th level.

I have a Full Plate armour with a +5 enhancement bonus, and no dex bonus. At caster level 20, what would my AC be? Specifically, does the enhancement bonus to natural armour stack with the enhancement bonus of the full plate armour?

  1. 10 + 9 (plate) +5 (armour enhancement bonus) +7 (natural armour enhancement bonus) = 31 (with stacking)
  2. 10 + 9 (plate) + 7 (natural armour enhancement bonus) = 26 (without stacking)

This is different from other similar questions (shield spell and shield enhancement bonus and enhancement bonus to armour) in that I need to understand what exactly is an enhancement bonus to natural armour. Being that in the AC tab of the core rulebook it's specified, in the other AC bonuses section (emphasis mine)

Other Modifiers: Many other factors modify your AC. Enhancement Bonuses: Enhancement bonuses apply to your armor to increase the armor bonus it provides. [...] Natural Armor: If your race has a tough hide, scales, or thick skin you receive a bonus to your AC. [Core Rulebook, pag #179]

From this it seems any enhancement that affects AC is lumped in one category, but it's not very clear. The question about enhancement bonus to armour would provide an answer, which is:

You don’t get enhancement bonuses to AC, you get enhancement bonuses to armor bonuses

But it lacks source and thus is non conclusive. If anyone could find a source on that then we'd have an answer.


1 Answer 1


They stack in this case, the rules for enhancement bonuses are

An enhancement bonus represents an increase in the sturdiness and/or effectiveness of armor or natural armor, or the effectiveness of a weapon, or a general bonus to an ability score. Multiple enhancement bonuses on the same object (in the case of armor and weapons), creature (in the case of natural armor), or ability score do not stack. Only the highest enhancement bonus applies. Since enhancement bonuses to armor or natural armor effectively increase the armor or natural armor’s bonus to AC, they don’t apply against touch attacks.


In this case you have two different enhancement bonuses, one on the armor, one on you. Since they're not applying to the same creature or object or ability score, they do stack.

See also this Q&A which comes to the same conclusion.

  • \$\begingroup\$ @Autongnosis The closest thing in the Core Rulebook I could find was the description of AC from pg. 179, where it mentions how to calculate AC and the different sort of bonuses you can get... you can sort of infer the same thing from there, but I don't think its as clear. \$\endgroup\$
    – Cubic
    Jun 2, 2020 at 14:51
  • \$\begingroup\$ D20PFSRD copied over a lot of material from the 3.5 D20SRD, which is where they got the quote from. The pfsrd is full of unmarked 3.5e, homebrew, and 3pp content, and has done stuff like move occult classes under the alternate rule systems sections when those classes are not anymore optional than the hybrid, base, or unchained classes. It's a nice resource for looking up rules on, but always try to correlate them on Archives of Nethys. \$\endgroup\$
    – willuwontu
    Jun 2, 2020 at 15:24
  • \$\begingroup\$ My problem is that it's never explicitly clarified if natural armour is separate from armour. Because if those are two separate things they should in theory stack directly since while they are two enhancement bonuses, they are enhancing different stats and thus don't interfere with one another. Can anyone point me to where exactly the rules for natural armour are? I can't find the original source... Archives of Nethys aren't helping, I need to delve deeper in there cause I can't find the source rule either. \$\endgroup\$ Jun 2, 2020 at 21:53
  • \$\begingroup\$ @Autongnosis that armor and natural armour are separate is specified in the AC calculation. I gave a page reference further up, but you can also ask a separate question about it if you like. \$\endgroup\$
    – Cubic
    Jun 2, 2020 at 22:18
  • \$\begingroup\$ @williamporter There is some 3.5 Paizo content on d20pfsrd.com, but not very much. There is a lot of third-party Pathfinder material, but it is all fairly-clearly marked. Certainly none of it is unmarked. I’m not aware of any homebrew there, though the line between third-party and homebrew can be blurry. And Archives of Nethys is an atrocious browsing experience (though, to be fair, d20pfsrd.com isn’t a good browsing experience). \$\endgroup\$
    – KRyan
    Jun 2, 2020 at 22:39

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