One question that came up in my group was this:
We have a player who is playing a Were-Bear that has a +2 on his Human Form power because he only transforms when he's VERY ANGRY (Hulk Style). Since this is obviously quite different from what this bonus is intended to be used for (moon phase transformation etc.) we where at first at a loss on how to handle it during gameplay.
I'm the GM and how I've decided to rule things is that he has to FAIL a Discipline Roll against a set difficult to transform, and he has to keep rolling every round of combat (and After combat) to see if he calms down or not.
He is +0 in Discipline and has the aspects of Easily Angered and Compulsive Drunk both of which have been used as justifications a couple times as a means of self compelling a transformation without doing a roll.
If he gets into a situation where either he thinks (or I think) that he could potentially be made angry enough for a forced change, I usually set a difficulty and have him roll (ex. He gets hit while in physical combat, he gets insulted in a social situations, or other RP specific conditions)
Once he's in combat AND has transformed I try to make it easy for him to stay transformed.
We use the 2D6 system (one +, one -, add em, use result with bounds of -5 to +5) so when in combat I make it so he has to get a perfect roll of a +5 to suddenly shift back, and once things cool down he has to beat a +2 or +3 (depending on certain circumstances).
Also to give the transformation an additional drawback if he fails to "calm down" after combat ends he goes into a kinda of compelled berserker rage where he starts attacking allies and enemies randomly until he can be calmed (Since he also has the aspect of Easily Amused I've made it so that his his fellow party members (or Observant NPCs) can chose to use a fate point to compel him to calm down by distracting him with either alcohol or shiny things (heh)).
Most of these mechanics emerged from seat-of-my-pants game-play moments, but so far has seemed to work.
What do you guys think? Have I totally mishandled this, or does it work?