From what I can tell with this spell, one of the Great Old Ones - Yig - is an allowed form. Am I missing something elementary in RAW to prevent it?
The attacks would be Bite (6d10), 2 Claws (4d8), Tail Slap (4d10). And a Con Drain poison that requires 3 consecutive saves.
EDIT: Wrong spell in the title
Yig is a Monstrous Humanoid, not a Magical Beast.
Plus, there's the little matter of having to have some portion of the creature, which I, as GM, would DEARLY love to know how you managed to get that and not be a grease spot.
Since a piece of Yig has no fixed price -- that is what the Eschew Materials feat is for. Technically, the average spell component pouch could also be assumed to somehow contain a piece of Yig, if the spell itself permitted you to do that.
Sorry, yes - Monstrous Physique, not Beast Shape.
I guess one could argue that since its an unknowable Great Old One, that the player would need to make a HEFTY DC Knowledge check to have enough knowledge of Yig to change into it.
And yes, he's an individual - but he's also a species, since he's one of a kind.
If you want to absolutely torture the intent of the rules and definition of species sure. Then again if we go into the dictionary, being declared a species generally requires two organisms capable of reproduction among several other bits of minutae. Since Yig (and Bokrug for all you Beast Shape lovers) are unique individuals who cannot make little Yigs/Bokrugs most biologists won't call either their own species.
Of course arguing that sort of thing is strictly academic since the general rule of thumb with PF rules is that if any part of your explanation for why something works features the word "technically" then odds are that wasn't intended and nearly any GM will treat such attempts with an icy glare at best.
Sorry, wasn't my intention to anger anybody - thank you for your feedback.
I see no problem with abusing rules. Abusing the rules of biology is how corn exists. Abusing the rules of electromagnetism is how radios exist. Abusing quantum mechanics is how lasers exist.
You can turn into green men with plant shape however
Which is strong.
If you know enough about Yig (or another member of Yig's species) to know what form to take, sure, you could turn into a kind-of-Yig. I'd wager that even Yig's followers probably don't know what Yig looks and moves like well enough unless they'd seen Yig in person.
You'd only get the stuff listed under the polymorph subschool and the spell, of course. Nice stack of natural attacks, but bite/claw/claw/tail slap is nothing crazy.