Help understanding possession

[Syries]

Hey, I'm currently in Return of the Runelords and was a bit unhappy with where my first character was going so with my GM's permission I retired that character and rolled up a new one- Vivisectionist+Beastmorph alchemist with an animal companion. GM gave his stamp of approval for this build, but I want to make sure I'm following the build by the rules.

Through Viv I can Baleful Polymorph my small cat A.C. into a squirrel for a massive Dex bump at level 9. Throw on an agile AOMF and I'm sitting at a passive 34 Dex before magic items and buffs.For the purposes of allowing my build to come online he's handwaving the headache of dealing with the saves by assuming the Fort save fails and will save succeeds (He's a nice GM)

If I use Marionette Possession on my now-squirrel A.C, because I retain my class, I should be able to then imbibe my feral mutagen for a Dex bump and the claws/bite without problem, right?

If I were to take a level in Master Chemyst, would I be able to use my Mutate ability while possessing my A.C?

As for feats, if my PC has power attack or lunge, can I use those feats while possessing my companion? Am I limited to feats that the Companion has only? Since I retain my class, would I get the fun sneak attack dice I get as a Vivisectionist?

[CMantle]

Yes you can use your mutagen ability. As written, the mutagen is not form-dependent, it just requires an alchemist use it. You are still an alchemist. An Elf alchemist who you steal a mutagen from, as a human, would effect you the same way it effects the Elf. Race/species has nothing to do with the effects of the mutagen, it simply has to be imbibed by an alchemist.

Yes you can use your mutate ability. It is non-reliant on any gear or form.

Yes you keep your feats. You can only use those feats if your current stats meet the prerequisites, however.

Yes you keep sneak attack dice.

Although this is not a polymorph spell, since you are controlling/using a different body you would use the polymorph rules.

"While under the effects of a polymorph spell, you lose all extraordinary and supernatural abilities that depend on your original form (such as keen senses, scent, and darkvision), as well as any natural attacks and movement types possessed by your original form. You also lose any class features that depend upon form, but those that allow you to add features (such as sorcerers that can grow claws) still function. While most of these should be obvious, the GM is the final arbiter of what abilities depend on form and are lost when a new form is assumed. Your new form might restore a number of these abilities if they are possessed by the new form."

Your mutagen and mutate ability are both abilities that "allow you to add features (such as sorcerers that can grow claws)."

Unless the form you assume, for this case a squirrel, makes it impossible to perform the ability or feat, you maintain it.

This is a cheeky build and I hate it, but I do believe it's legitimate. Cheers

[CMantle]

All I would say is be careful... Yes these are nice buffs, but Marionette Possession specifically says that the body retains its hit points. And with familiars having 1/2 their master's hit points, you're taking quite the hit to HP and risking the death of your familiar for a nice buff. Unless you are of evil alignment you would probably have some sort of reluctance to risk your familiar's life, so recklessness in this body should be heavily discouraged.

[Cevah]

A squirril is a Diminutive creature, therefore has 0' reach. You must enter a enemie's square to attack it, provoking an AoO.

/cevah