I've thought of a new rule that I want to implement! So pay attention!
Whenever magic is used the caster must determine the exact amount of power he/she wishes to use. Normally up to the highest rating of the most relevant discipline. Each point represent one die which I then cast to determine the result of your spellcasting. This rule make it entirely possible to vary the amount of power your character put into each spell (logically the more power the more tiring it is) to achieve their desired effect.
Now, it's also possible to pump more power into a spell than your rating allow, but doing this is even more seriously tiring on the mage, if not directly harmful. The advantage of this is that you can achieve more powerful magic, but the consequences can be severe. Normally this means that a random effect may occur as a result of the Overextended magic, or the mage may have to accept it as a backlash that cause physical damage upon their body, or who knows what else.
What does this mean to you? Well, basically just that you need to tell me (in a spoiler) how much power you use every time you attempt to cast a spell in game.