Biped and the Eidolon Mount feat, What changes?

[Xelethor]

If a chained summoner has a biped eidolon and then takes the "Eidolon Mount" feat, do they need to recalculate the eidolon's starting strength / dexterity and their base saving throws when the eidolon uses change shape, and does the eidolon lose the claws evolution and gain the bite evolution when doing so?

[Java Man]

The mount evolution can only be taken by quadraped and serpentine eidolons, so I do not understand your question.

[Val'bryn2]

There's a feat in Ultimate wilderness that lets your eidolon shift forms, called Eidolon Mount. I was confused when I first read the post, too.

[Jeff Morse]

change shape oes not alter any abilities so leave them alone. you would adjust carring because of 4 legs. if the base form gets claws than yes, so hands become claws and so forth. acts alot like a polymorph effect

[Xelethor]

Jeff Morse wrote:

change shape oes not alter any abilities so leave them alone. you would adjust carring because of 4 legs. if the base form gets claws than yes, so hands become claws and so forth. acts alot like a polymorph effect

So this feat lets you effectively keep the base str/dex and saves of a biped eidolon while in quadruped (mount) form, but you lose the biped's free evolutions to gain the quadruped free evolutions? or are you saying you keep the biped's free evolutions when changing shape into a quadruped?

If its the latter does that mean you do or dont get the quadruped form's bite attack?

[willuwontu]

Here's the feat.

Eidolon Mount (Combat) wrote:

Your eidolon is capable of serving you as a combat-trained mount. If the eidolon’s base form is not quadruped or serpentine, it also gains the ability to transmute its physical body into a form suitable for you to ride. This functions as the change shape ability, except the eidolon’s base form changes to either quadruped or serpentine and its size changes to be one size category larger than its summoner’s base size. Unlike other changes to size, this ability doesn’t increase the eidolon’s ability scores, reach, or weapon damage beyond that of its true form. (However, if the eidolon’s size is reduced by this ability, its reach and weapon damage are adjusted accordingly.)

If the eidolon’s base form is not quadruped or serpentine when it gains this feat, it chooses which base form (quadruped or serpentine) to assume when using this ability. The eidolon cannot choose a base form that is not available to its subtype with this ability. If both base forms are available to the eidolon’s subtype, it can change which base form it assumes when using this ability whenever it gains a new Hit Die. The eidolon can select evolutions that have either base form as a requirement, but any evolutions that require one of the base forms (but not the other) provide no benefit while the eidolon is assuming the shape of its other base form.

When you use the change shape from biped you use the statistics of your new base form. Any evolutions that only apply while in biped form are lost while you are in your other form. The size change does not modify the ability scores, reach, or weapon damage of the eidolon unless they would be reduced.

[Xelethor]

willuwontu wrote:

When you use the change shape from biped you use the statistics of your new base form. Any evolutions that only apply while in biped form are lost while you are in your other form. The size change does not modify the ability scores, reach, or weapon damage of the eidolon unless they would be reduced.

So you would lose the biped's free evolutions (to gain the quadrupeds) and you would actually change the biped's "Str 16, Dex 12, Con 13, Int 7, Wis 10, Cha 11" stat array to the quadruped's "Str 14, Dex 14, Con 13, Int 7, Wis 10, Cha 11" stat array each time it changed form?

[willuwontu]

Xelethor wrote:

So you would lose the biped's free evolutions (to gain the quadrupeds) and you would actually change the biped's "Str 16, Dex 12, Con 13, Int 7, Wis 10, Cha 11" stat array to the quadruped's "Str 14, Dex 14, Con 13, Int 7, Wis 10, Cha 11" stat array each time it changed form?

Yes, as it's only the size change that doesn't modify the ability scores, not the change of base form.

[Melkiador]

Quote:

Change Shape

A Creature with this special quality has the ability to assume the appearance of a specific Creature or type of Creature (usually a humanoid), but retains most of its own physical qualities. A Creature cannot change shape to a form more than one size category smaller or larger than its original form. This ability functions as a Polymorph spell, the type of which is listed in the creature's Description, but the Creature does not adjust its ability scores (although it gains any other abilities of the Creature it mimics). Unless otherwise stated, it can remain in an alternate form indefinitely. Some creatures, such as lycanthropes, can transform into unique forms with special modifiers and abilities. These creatures do adjust their ability scores, as noted in their Description.

[Derklord]

Quote:

Some creatures, such as lycanthropes, can transform into unique forms with special modifiers and abilities. These creatures do adjust their ability scores, as noted in their Description.

Eidolon Mount very much transforms the Eidolon into a unique form, i.e. you don't use any existing polymorph spell. What you bolded only overrides the normal ability score changes of the polymorph spell (that we don't have anyway). Thus the ability scores do change (without size bonuses/adjustments as per the feat text).

­
The problem with Eidolon Mount is that Change Shape is supposed to use a stated polymorph spell. That polymorph spell tells you what do change, but without one, we lack information. Presumably the virtual polymorph spell says you use the stuff of the new base form, but how far does that go?
Per the polymorph rules, you lose all natural attacks and ex/su abilities dependant on the original form, which does include the free evolutions, but do gain all the target form's natural attacks (which includes the attacks from free evolutions), as well as the base speed. For the sake of not-getting-a-migraine, I think we should assume that the Eidolon gains the regular free evolutions of the new base form. The feat says (or at least very strongly indicates) evolutions work, so your chosen evolutions are covered.

The remaining question is the save progression - normally, a polymorph effect doesn't change that, but this is a pretty unique case. I can really see it be ruled either way.