Aurae, Aegides, and Spontaneous Casting

Hi all,

For spontaneous casting, does the bonus or penalty from an aura get factored in before or after division? What about the penalty for casting in a foreign aegis? On one hand, it doesn't make sense that a hostile aegis or aura would be less effective at factoring out spontaneous spells than formulaic spells, but on the other hand, should every apprentice with 0 in all Arts have a 50/50 chance at sponting any first magnitude effect, within the average covenant aura?

Apologies if this has been answered before, but the forums' search functionality isn't very robust.

Thank you!

The aura is part of the Casting Score (see AM5 p.81), which means it is added before the division that yields the final Casting Total. So are words and gesture modifiers, the fast casting penalty, vis bonus, ceremonial casting bonus, and pretty much everything I can think of except...

... the Aegis penalty, which applies directly to the Casting Total, after the division (and the much rarer PeVi guideline "reduce the casting total for all magic..."). Oh, and Confidence points I think.