There were a number of threads on various message boards regarding exactly what the Polymorph Self, Polymorph Other, and Alter Self spells could do. Someone sent a message to Sage Advice to help clear things up. They received a response a short time later. The following response has only been edited for better formatting. All typos are left in their full glory. The Sage's answers are in bold. If you were the one who sent the original message to the Sage, please let me know; I'd like to put more accurate mail header information in here including the date so we know how this relates to current and future errata.
Will a character polymorphed into an Annis get the Claw/Claw/Bite attack routine?
Yes and no. You get the assumed form's natural weapons. To use those weapons, you have to use the normal two-weapon fighting rules (if there are three or more natural weapons, only one can be the primary weapons, the others are off-hand weapons.
Does Shapechange work the same way.
Yes.
Can monsters with high BAB also use a (high damage) natural weapon as a "regular" one (AB/(AB-5)/(AB-10) etc.?
No, but characters who have assume the monster's form *must* do so.
Will he get the Annis' extraordinary abilities?
No, the spell description specifically says you don't get extraordinary abilities.
The spell description also lists several (Rake[Ex], Constrict[Ex] and Low-light vision[Ex]) extraordinary abilities as examples of the "natural" abilities you gain in the new form. Is this a mistake?
Not in the spell, in some cases, the creature description is wrong (rake and constrict aren't extraordianry).
How do you decide if an ability is "natural"?
In general if an ability is not listed as extraoridnary, spell-like, or supernatural, it's "natural."
The revised spell removes the disorientation penalty, but still refers to it later in the spell description. Does the disorientation penalty (and the will save) still apply?
No. Mentioning the penalty in the errata was a mistake.
What happens if a caster polymorphs into a creature with a flying speed of more than 120 (like many dragons)?
The flying speed is reduced to 120.
Do you need to be familiar with a form to Polymorph into it?
Yes.
What does "familiar with" mean anyway?
Seen the creature or studied parts of it works for me.
When a character change size his equipment also change size to mach the new form (if the new form uses equipment). Does weapon damage also increase or decrease with size?
Yes. Se DMG p. 162 for the details.
You cannot change into a "larger, more powerful version" of a creature. Can you polymorph into the creatures you get by applying the changes implied in a creatures listed advancement? Example: Large Wolverine +8 str, -2 dex, +4 con, +3 natural armor, -1 AC/attack.
No. You can only change into creatures that are listed independently in the MM (like the various age categories of dragons). A large "Wolverine" is just a really large "Wolverine".
Does Polymorph Other stack with Enlarge?
It depends on the order the effects are applied. If you polymorph an enlarged creature, you get the typical size for the assumed form, you can, however, polymorph a creature, then enlarge it.
Does Polymorph Other stack with Alter Self?
As with enlarge, it depends on the order of the effects.
Alter Self: "Your body can undergo a limited physical transformation, [...]. If the form selected has wing you can fly at a speed of 30 ft with poor maneuverability. If the form has gill you can breathe underwater." Are the possible changes listed (extra limbs, wings, gills) the only alterations possible?
No, they are only examples.
What else is possible? [I suggested Scent, Low-light vision, Darkvision or Blindsightis]
The entire sample list shown above is right out. You could, however, give yourself fins, fur, fangs, or claws, or a tail.
Before you ask:
fins: swim speed 30
claw damage 1d4
bite damage 1d4
tail slam damage 1d3 (+2 climb and balance)Can you have more than one change in effect at the same time (like wings and gills)?
Yes.
Can a creature with "monster" attack routines (like a Half-Dragon's 2 Claws and Bite) use those when polymorphed into a creature with similar attacks (like a Troll)?
I'd think so.
(Regarding extraordinary abilities...) How about [I mentined several categories of abilities I thought might be natural, like sensory abilities or abilities based on appearance]?
No (except for constrict and rake).
Alter Self:
Do you have to take the form of a specific creature or are the changes made to "your own" body?
You can just change your own body.
Can you make more than one alteration (wings and gills and claws etc.) each time you cast the spell?
No, once change at a time.