Shape Changer

You could start out as a wart hog and work your way up to a crag or elemental or whatever, and as you progressed the length of time you were in your "new body" would lengthen.

Uhm, sounds like a Druid or something to me.
Please try making a Layout and add more info for this CC.
For now I am judging you with you're idea.
I am not really sure what are you thinking but I think this is like a Special Profession with a "Form Level" like is you use "Warthog" for alot of time you would change into a Big Boar, This sounds intresting.
I might give is "8.50/10", If you make a Layout and you put alot into it^^.

I find that before u start making a thread you should actually put effort into it, i personally am not a fan of threads that start with 'can some1 give me a build' or 'heres an idea, plz use it to make something nice'.
As for the class: This is imo a bad idea because the class would be so incredibly different from the other classes and once u reach lvl20 (which is very soon) the fun is over. It's all about balance. If we take a quick look at the Druid in WoW u'll experience that the concept is nice but it just doesn't work because the Forms, 'lion form, bear form', are much weaker/stronger than the classes they are based on, Rogue, Warrior etc...
If u rlly want this class, then i'd suggest u start giving a whole lot more details