Some various thoughts about Shapeshifting in the LoGaS discussion group.
The short answer is, yes, I’ve used these (shapeshifting) rule tweaks in my campaign and in convention play. I try not to use convention play for any examples, because I feel Players in a 4 to 8 hour game that only happens once (or maybe continues) will do madcap things and make choices that are certainly NOT long-term immortal mindset.
IMC (in my campaign), the GM is very forthcoming with OOC warnings, and impartial to Players going across forbidden lines where they might/shall lose control of some aspect of their PC. Sometimes that becomes a story about ‘getting back’ to normal once the crisis is over. Sometimes it becomes a learning experience where the PC discovers something new about themselves.
Generally, I find Players do NOT want their PC changed by the GM and so they take these warnings seriously. In conventions, I see a more mixed reaction, where the Player may see more ‘spotlight time’ if they take the chance and dance across the Forbidden. There are certainly some Players who are OK torturing their PC concept and grabbing more face time with the GM.
As I say above, I’m pretty open and informative as a GM. I consider my advice to Players as not only their own Expertise (Attribute wise and/plus immortal experience) but also I definitely want it to be more than clear that if you go into a Forbidden Art, you may find you lose something of your original PC concept. Or you may find something new and wondrous about your PC, or perhaps you’ll just be trapped in a story line about how much your PC regrets having pulled that trigger. As seems obvious in the rulebook, owning a power sometimes means living with a certain forced perception.
As the GM, I’m your partner in perception. Just like Stuff changes how you interact with the Universe, and how people tend to see your PC, I think bigger pools of power, Exalted, or Primal, or Terrifying, etc, will tend to warp your PC’s perceptions to align with the power.
In other words, is Dworkin mad, or does he just see the Universe in a way no one else does?
GM responsibility here is not to steal authority from the Player or deprotagonize him/her, but to act as the altered perception filter. This is certainly dangerous territory for the Game Master. A bit too much, and the Player thinks you’ve ruined the PC. A bit too little, and it appears the Universe rewards crazy risks with insane amounts of unearned power.
What is the guide? Most rules do not actually address crossing the line into Forbidden Arts.
I think the guide is actually story tension. The GM and the Player both want the story to have tension. It isn’t going to be fun if the choices are gone. It’s not going to be fun if the tension is gone, or if the GM keeps saying, ‘No, your new bloodlust means you attack your friends on sight’. At the same time, it cannot be ALL FUN because there are costs to breaking the Forbidden. And the PC cannot be unchanged because they DID choose to touch/claim/swallow the Forbidden.
It’s also not bad if the other PCs are now looking at the changed PC as if they are a train wreck. Story tension, in effect, for everyone.