I've been playing around with a variant on Performance Magic. Tell me what you thing.
Performance Magic (Minor Supernatural Virtue)
Performance magic is a non-Hermetic, hedge practice of spellcasting. When choosing the virtue, choose any mundane ability such as Hunt, Music, or so on. Also choose a magical subject matter of the scope of a Minor Magical Focus, such as inducing emotions or hunting. Performance magic allows you to cast magic within this focus using the relevant Ability.
To create the effect, you must make an appropriate performance. Roll Pre+Ability against an ease factor equal to the Hermetic spell level you wish to replicate; if you reach it, the spell succeeds and is maintained for as long as your performance does. This is equivalent to the Concentration (+1) duration (modify for Range and Target as usual). Failure simply indicates the failure of the spell to take effect, not necessarily any dire result (such as loss of fatigue or so on).
The practice of performance magic must always use the appropriate "gestures" (+0 to spell casting roll). Although words aren't always necessary, some traditions do require them (in particular, the use of song magic to affect emotions is traditional). Again, this has no bearing on the spell casting roll (+0 modifier, as if using normal tone).
The supernatural aura modifies this roll as normal. So does the Penetration ability.
Hedge practitioners of Performance Magic are usually affiliated with the Magic realm, although members of all Realms are possible.
[An Hermetic wizard casting a formulaic spell would be slightly less flexible, but will get to add his Form and has a +10 leeway. Combined with other Hermetic techniques such as the use of raw vis, talismans, or ceremonial casting the raw power of Hermetic magic is far greater. Hermetic magic also allows for different durations, and of course offers a plethora of other issues such as enchanting devices. Performance hedge magi still do have significant capability of casting vary varied spontaneous effects with their mundane skills, however.]
If you're an Hermetic magus, you may use the Ability as a non-Hermetic Technique to cast spells in the area of focus. You can cast the spell as if it was a Spontanous spell, replacing the Technique with the Ability. You may choose to cast the spell with the Performance duration, or with any other Hermetic duration.
The main advantage of doing so is that such spellcasting is far more discreet than standing around mumbling in Latin and making strange motions. You may also implement any corresponding technique related to normal Hermetic spellcasting, such as using an attuned talisman. The main disadvantage is that you cast the spell as a spontaneous spell, which usually means you must expand fatigue and that its power is limited. Using the single Ability instead of the appropriate Art may be an advantage or disadvantage, according to your scores.
You may choose to cast an effect using only the Performance Magic hedge methodology, you need not use the Hermetic methods of spontaneous casting.
Using performance magic is usually discreet. It doesn't appear that you're working magic, unless the spells themselves have some obviously unnatural effects. It generally requires a Perception + Magic Lore roll of 12+ to realize you have cast magic. This allows magi who use Performance Magic to cast spontaneous spells without incurring undue attention.
A similar roll might be required to guess at the Form should a fast-cast intervention be required, although a simple guess at the Form usually suffices if the use of Performance Magic is suspected.
It is possible to cast several spells at once with performance magic. This requires piling on one spell onto another in an increasingly complicated feat of skill, so may only be attempted using the Performance duration. The caster simply attempts to complicate his performance, adding another check for the new effect but with a +3 to the ease factor per extra effect currently maintained by the performance. It isn't necessary to roll Concentration as if casting a spell while maintaining another - although concentration on the performance needs to be maintained regardless.