I really, really think we need something like this, especially given how this can be tricky.
And I'll inaugurate things with my own spell idea to submit
There's this possibility that, in the future, Hiems would want to invent a spell to freeze people up, to immobilize them without killing them or endangering them in any way.
By RAW, this is pretty simple: ReCo, with the "freezing" being cosmetic only (which is made easier by Hiems sigil).
But, the problem is, I think this kind of spell is perfectly appropriate for him, and would like it to fall under his focus, because of this. But I don't think a simple cosmetic effect would allow this (I'd disallow it as a GM)
So, my question is: If I add Perdo and Ignem free requisites (no +1 mag because it doesn't enhance the effect, like damaging people), would you feel this'd be okay or not?
Balance-wise, it'd be more powerful now that a simple ReCo, because of the focus. In the long run... I don't know. On the one hand, that makes 4 arts to raise, but on the other, there's a focus.