For the same reason why I didn't like the idea you were going to copy something from Reinhard; just because a canon character can do it, doesn't mean we'll allow everyone to. And in Priscilla's case, not only is she herself a skilled magic user her spell is explicitly mentioned to be not only powerful, but also energy consumptive. The fact you never specified it and tried to make it sound like an original spell made it more worrisome, because for all we know you could be trying to get the same power without the drawbacks.

The devil is in the details, and while the other GM's may have a more casual approach to CS making, I will be more thorough. Hence why I want to implement a list of the spells any character capable of magic can use, including it's leveled variants. This way we won't have vague "I can do [X] because I'm able to use [Y] magic" without anyone knowing what other tricks you plan to pull.