Imp Familiar change chape question

[Ethereal Gears]

So the change shape ability of an imp states it can transform into either a boar, giant spider, rat or raven, with the ability being based on beast shape I. An imp is Tiny and a boar is a Medium creature. Regarding the change shape monster ability, the Universal Monster Rules state: 'A creature cannot change shape to a form more than one size category smaller or larger than its original form.'

Does this mean that imps get to violate this rule with their change shape ability, or do they turn into boars with the Young template or something?

[Sir Eldon's Head]

I just took a Cacaodeamon Improved Familiar and I have both the same question regarding the venomous snake and a related question. How would I calculate the poison DC for the venomous snakes bite? Is the the venomous snakes base DC or do I increase the DC based on the higher effective hit dice and constitution?

[Ethereal Gears]

I'm pretty sure any special abilities of a familiar that are based on Hit Die use your character's Hit Die if it's higher than the HD of the base familiar. Same goes for special abilties gained via change shape, if the polymorph spell the familiar's change shape is based on grants access to, in this case, poison. That's Beast Shape III and above, methinks.

"For the purpose of effects related to number of Hit Dice, use the master's character level or the familiar's normal HD total, whichever is higher."

That's what the rules say. If the DC of special abilities ain't 'an effect related to number of Hit Dice' then I honestly don't know what is.

EDIT: Regarding the size thing, I do suppose we might both have just run into 'specific trumps general', but I'm unsure of whether that's actually an ironclad axiom of PF rules or just a sort of commonsensical argument that usually but not always applies that people like to toss around...

[Ethereal Gears]

Bit of a bump. Anyone got any sort of conclusive info on this?

[Neonpeekaboo]

IMO, Specific Imp rules trump Universal general rules.

[Taube]

I actually don´t think so.
Compare the HD entries for animal companion and familiar. It clearly states the direkt number of extra HD the animal companion gets, while stating for the familiar that it acts like it had more HD (Master or Familiar, whichever is better) for HD-based effects.
For me, this says that HD-based stuff like poison doesn´t skale up.

As for beast shape: I think "legacy item" beats general rules in some cases, especially when talking about a creature whose stats have been around so long and which should work as usual. So Boar shape is ok, but an exception to the rules.

[Ethereal Gears]

Yeah, I'm leaning in that direction as well. Seems rather harmless, allowing the guy to grow to Medium size. Might actually make doing a melee-focused familiar, while still abysmally under-optimized, a tad more feasible. Though probably that'd still not matter much, since if you wanted the imp to fight you'd probably cast an actual polymorph spell on him to boost his ability scores rather than rely on the somewhat less powerful size shift incurred via change shape (or "change chape", as I for some ineffable reason called it in the thread title :P).