Confusion about eidolons' max armor bonus

[The Mailman]

Is anyone else mildly confused by the max armor bonus explanation?

So, the armor bonus column in table 3-3 is supposed to be the "base total armor bonus" and it can be split between "an armor bonus and a natural armor bonus." So, does that mean it doesn't affect things that give an "enhancement bonus to armor or natural armor" (eg, barkskin). What about shield bonuses? Do they fall under the prohibition on armor? The Shield spell?

Similarly, at first glance, this sounds like it means that you can use any combination of evolutions or magic items or spells that grant "armor" or "natural armor" bonuses, but that they cannot total more than this number. That's odd, since at first level this number is 0 and all eidolon base forms start with a +2 natural armor bonus. Does the Armor Bonus column only refer to increases over the initial +2? How does the INA monster feat fit in?

Also, the explanation says that "this number is modified by the eidolon's base form and some options available through its evolution pool." Does that mean that when you take the improved natural armor evolution that it modifies the number in the column by 2 as well? (meaning, you've increased the cap so you can still use spells and other magical means to increase AC without accounting for the "+2" you get from your INA evolutions)

Am I missing something explained elsewhere?

[Okugi]

The prohibition on armor only applies to physical armor, not bonuses granted through magic. As such, yes, you can have all of your armor bonus be natural armor, and have effects such as mage armor and shield to further increase your eidolons AC. Just have to keep in mind that bonuses of the same type don't generally stack. The PRPG book has a better and more detailed description on what armor types are stackable.

The armor column is an additional armor bonus granted in addition to any other source of armor. The bonus granted from increasing in size and the bonus granted from the improved natural armor feat all stack together, being that they are enhancements which state they increase the bonus.

To answer the third part, yes. By stating the number is modified by the base form and evolutions, you do indeed increase that columns number by the base amount, plus any amount of improved natural armor evolutions you've taken.

It looks like you read it as also capping the AC of the eidolon. It doesn't do that, nor does it read anywhere that it does so. As such, the column is simply the starting point when determining the AC of an eidolon. Just like the armor for a normal PC. Your eidolon still gets dex bonus, spell bonuses, etc.

[The Mailman]

ah -- for some reason I was reading it as a cap, like the cap on attacks. All the rest makes sense then.

[Ravingdork]

As written there is no reason not to always make it all a natural armor bonus.

If you make it an armor bonus then a plethora of things will no longer stack with it (mage armor, bracers of armor, etc.). However, if you make it all into a natural armor bonus then you can benefit from mage armor, bracers of armor, barkskin, or amulets of natural armor (the latter two of which specifically state they add onto existing natural armor bonuses).