Fun is part of balance too. If an element of the game is broken, it is fun for only one side, at most, if not nobody.
And balancing Descent is near impossible.
Maybe you don't think that adding a yellow die and a black die is kind of strong, but for sure, try to play it or against it, and rolling blue + red + yelllow in attack, and grey + black in defense is kind of strong, further since it doesn't needs you to spend any money. And black + grey die in defense is Really tanky ! In fact, it is like the werewolf had the Runeplate armor !!
Don't forgive that the werewolf form doesn't needs you to spend any gold for him. So, indeed, it is strong, but maybe not as you wish you to be. And adding more advantage to it would be really broken. And using you idea to give a leap attack with a dice bonus would mean that the werewolf would do normal attack with only Blue + Red ? in act 2, it's neally useless, even the Raven flock has Blue + Red + Yellow dice on each regular attacks.
I'm going to think back of it, but really, you need to try it to see for yourself, because it not, this discussion is hard since your lacking playtest and gameplay.
Finally, for the action or fatigue, let me show you an example.
You're in druid and need to change to werewolf. You spend an action, you can. If it's fatigue cost, if you don't have it, you can't, you need a rest action before, and may be killed. In short, you always have an action to spend to change form but you may not have the fatigue for it. The Ovelord may stun you but you still have at least 1 action left, but the Overlord can make you lose all your stamina without any limitation. So, action is the best way. I could have create another way to change shape by XP cost, but I it was waste of skill
Edited by rugal