Flawless magic isn't about perfection, but it is about mitigating risk.
I beg to differ with that interpretation of the word "flawless", but hey.
The word means it, yes. But the use of Flawless in Flawless Magic is evocative, and not literal. I'm evaluating the virtue, not just its name. There are still numerous situations where one can botch with Flawless Magic, for example, my view that ritual spells are always cast with stress die and is at least 1+# of pawns of vis is one really important use for Flawless Magic. High level ritual spells become manageable with a combination of Flawless Magic, Golden Cords, and perhaps Careful Sorcerer.
Our houserule was a bit simpler compared to the previous examples.
If you are using Multicasting:
- your got the number of extra botch dices as many times you want to cast the spell in the turn
and - you forfeit all botch dice decrease from your Mastery levels.
It turned out to be a powerful and definitely risky endeavour.
In the city, in combat, with mastery 3 fast casting four PoFs are terribly risky. (13 Botch dices = 3 divine aura + 2 combat stress + 4 number of copies + 2 fast cast)
And of course casting rolls are made for all four PoFs.
If the same mage casts it without multicast it is a simple task. (4 botch dices = 3 divine aura + 2 combat stress + 2 fast cast - 3 mastery level)
Casting 4 POFs in a city is risky on its own and in my understanding it isn't defensive, unless against something like Mighty Torrent of Water. Keeping fast cast for defense only seems to solve soapy problems for me.