And a PEACH of the Slaadborn Rager.

Another interesting class! This one seems somewhat...unfocused. Or at least not certain where its focus should be. And not intentionally like some of the other classes in this contest. It appears that there is a disconnect between the class abilities and the prerequisites. The class abilities make for a PrC that's best played very barbarian-like. Lots of raging, high physical abilities, high BAB, lots of melee. They also seem to build on a character that can change her own shape through some ability (as opposed to someone changing her shape for her. At least, if she wants to make regular use of the Slaadform ability. I hope I'm not wrong in seeing things this way.

Then you look at the prerequisites. First, there's nothing precluding someone from being the target of Polymorph and then entering this class. If you actually want the character to change her own shape, make it explicit in the prerequisites. Second, other than the high BAB requirement, nothing prevents someone from dipping barbarian for 1 level and having all of their other levels in a non-barbarian class like Druid or Wizard. In fact, these would be easy ways to fulfill the shapeshifting prerequisite, were it not for the fact that none of the class abilities other than Alternate Form provide for any continuation of non-barbarian class abilities.

So, barring racial shape changing abilities, a character can only become a slaadborn rager by being barb1/druid5/other full BAB class 3 or barb 1/wizard 3/other full BAB class 5. Which is a lot investment in abilities that aren't really supported by continuing the class, unless you go the druid route. And even then, all you get is more wild shape. Perhaps this isn't the most strident criticism since the slaadform ability does give limited shapechanging to even those who aren't able to do it themselves, but it's something to think about.

Mania: I like this ability, but I wonder about how you've written it. Specifically, the line about how the ability deals Wisdom damage while giving a corresponding bonus to physical ability scores. That strikes me as dangerous, since the Wisdom damage wouldn't go away after the duration ends; it has its own fixed healing rate. So you could only use this ability once, maybe twice a day before your Wisdom hits dangerous levels. Especially at higher levels. I'd change it to wording similar to the Drunken Master's Drink Like a Demon ability. Unless this was your intent, in which case carry on !

Slaadform: Another interesting ability, but it needs some clarification. Out-of-the-box slaadi have more hit dice than you could ever have when you change into them, based on this ability. How do you reduce their hit dice? What abilities are kept and lost? I don't think that it would be outrageous to just let a slaadborn rager just turn into the base slaadi without the hit dice reduction, as long as they are within the restrictions of the ability they use to shapeshift. Also, I assume that you gain or don't gain special abilities/qualities according the rules for the method by which you change your shape. If so, you should probably say this explicitly.

Chaos Form: Again, Wisdom damage seems too high a cost here. I'd suggest just a temporary reduction in Wisdom until the slaadborn rager changes back rather than actual Wisdom damage.

Finally, there appears to be a small typo on the half-slaad template. The natural armor listed doesn't match with the amount in mutation 4 of list 1. Which is it?

Those are my thoughts. I hope they're helpful. Great class!