mmh...ok, this i like. so this makes it more of a bet with a "high risk, high reward" kind of system. you have agency over your casting in the sense that you can decide how much "power" to allocate to it, while increasing the risk of blowing in your face.
this is good, but still aesthetically goes in another direction compared to what i wanted to convey here. the guess action in mine does not have any advantage or disadvantage, no matter how you do it, and in that way you are completely blind to fate and luck. one might consider it pointless for that, but to me the fact that you have to take active part in abandoning yourself to luck has meaning.
in your system the image is that of someone who treats magic more like a pressure valve, which isn't bad i want to reiterate, just different; i'm thinking about a game with these two different kind of approach to magic as a differentiation in class, uhuh, i think that would really be cool.
on that note, if in the future i wanted to make a full fledged game and returned to these ideas plus yours, can i use it with credit?