So I hit 4th level, and I found a really nice creature to transform into, but I hit a bit of a rough patch when I conformed with the rest of the players. Here's the Wild Shape entry:
At 4th level, a druid gains the ability to turn herself into any Small or Medium animal and back again once per day. Her options for new forms include all creatures with the animal type. This ability functions like the beast shape I spell, except as noted here. The effect lasts for 1 hour per druid level, or until she changes back. Changing form (to animal or back) is a standard action and doesn't provoke an attack of opportunity. The form chosen must be that of an animal with which the druid is familiar.
A druid loses her ability to speak while in animal form because she is limited to the sounds that a normal, untrained animal can make, but she can communicate normally with other animals of the same general grouping as her new form. (The normal sound a wild parrot makes is a squawk, so changing to this form does not permit speech.)
The bolded part is where the problem arises, and is the argument that the other players showed to me. The requirement is that I must be "familiar" with the creature that I wish to transform into. And I guess that makes sense.
What doesn't make sense is how does one determine "familiarity" with a given creature? Do I have to make a Knowledge check every time I want to transform into a creature, failure meaning I cannot transform into that creature? Would this check have to be done for every animal I want to turn into, such as a common deer, or a monitor lizard? Do I have to have encountered the creature, in combat or otherwise, in order to transform to it? It's not really defined anywhere, nor is there really any good context.
Is this something that falls into GM FIAT, or is there some sort of RAW basis that can be used to determine if transforming into a given creature is valid?
Knowledge Nature is enough following the DC to identify the animal as usual.
I as a GM only make my players to roll with the DC is more than 3x the Druid Level.
And I usually use the environment BG for reference.
As a player, I've never been asked to defend this, but if I had to my explanation is that he took a 20 on a knowledge check during down time to study a wild selection of animals... because ya, he is a druid... and that is kind of their thing.
That clause has a good place in games where animals in the bestiary might not exist in your game world, or might be literally unheard of.
As a thought experiment, lets take the Cave (Dire) Bear with a lvl 6 wild shape. Wild Shape (6) will give you the following cave bear abilities: Low-light vision, scent, natural attacks, and grab. Assuming cave bears are neither exceedingly common or rare the DC to learn all of that is 32 (17+0+5+5+5 under a reasonably harsh interpretation of the knowledge rules, one freebie and three additional pieces of info.)
Can your druid take a 20 and pass that DC during downtime? What type of circumstantial bonuses would he need to pass that DC? Did he do that?
Now that I've finished my thought experiment, I think my druid will need to buy a Pathfinder Chronicle and a Cracked Magenta Prism Ioun Stone before level 6. Because right now he is a little short, but is still ok to turn into an eagle (5 Common Animal + 1 CR + 0 Freebie Fly + 5 Natural attacks + 5 Low Light Vision = 16).