Can a Rustic Craft Mage, from HoH:S pg 131, use magic to speed up the crafting process?
The virtue seems very powerful, and looks like it blends some of the better parts of learned magicians with viktir, but the utility of the virtue appears to basically depend how fast you can craft an item.
Like the hiding the spell as craft seems of limited cute use, the creating charged items with a craft roll instead of a season seems the best, good enough that the bonus based on shape and material isn't that important.
The total bonus is capped quite low, so if you're willing to add writing and an image you probably don't need the base item for anything.
I guess using Rego From to craft the won't work, because that roll doesn't use craft right?
How else could it be done fast?
We could choose a craft that is easy to do quickly, such as stitching an image, or carving small figurines?
You cannot replace your character's Craft with Finesse and speed it up by magic like in HoH:S p.60f Rego-crafting.
But you can negotiate with your troupe about magically made equipment to speed up your character's work, until crafting the object takes "as long as a Ritual spell of the same level would".
It is not clear whether a character can have the virtue without its flaw, though I'd allow it, but it is clear than an Ex Misc of that tradition must take both.
The virtue that I like most from the Rustic package is the minor virtue, which I consider an excellent virtue... for a character who does not have Flaws ruining spontaneous magic.
It flat out contradicts the flaw, so is incompatible. Kind of like have Gentle Gift and Blatant Gift at the same time.
Of course, nothing prevents you from making a Diedne Rusticani NPC... but you can then just create exactly the virtues you want for an NPC, to get exactly what you want.
I've played two, with the first an example of what NOT to do.
Speeding up: Use C&G rules where a higher skill translates to decreased time crafting. "Average" quality requires a Craft Level of 6. If you double the Workshop total, you halve the time. Use leadership to have journeymen add 1/2 their ability to your workshop total. It is very easy to get absurd totals this way, and craft in 1/4 or less the "normal" time.
Utility: Mechanicals really depend on spontaneous charged items or LEI's in the L15-20 range that can be made in mere hours. Use virtues that add to Casting Total (Not Casting Score) such as the aforementioned Spell Foci, Special Circumstance, Cyclic magic, Item of Quality (Work Glove), Self Confident, or a pre-errata Talisman. A casting score of 4-6 suddenly turns out consistent L20 effects. A mechanical really should have "charms" ready made for just about any effect L20 or lower.
They can sell LEI's for a profit - they get a lower profit margin per item due to the increased cost to make, but can sell a MUCH higher volume than even the most prolific Verditius.
Many such Virtues - like ArM5 p.41 Cyclic Magic, ArM5 p.49 Special Circumstance - were errataed in the meantime, not just the Talisman. ArM5 p.19 Using Confidence "spend Confidence Points on most rolls to get +3 to the total per point spent" is still an itsy bitsy ambiguous, but applies only to rolls - which a Rusticanus built by the book does not make for spontaneous magic. So does HoH:MC p.124 Items of Quality.
But HoH:S p.132 Spell Foci still add to Casting Totals: this has indeed never been errataed. I cannot say, whether it was just overlooked in its cranny when sweeping out the books, or was intentionally left in.
Best talk all this over with your SG when creating the character with Craft Magic, with books and errata at hand. If you happen to be the SG making an NPC, don't optimize with means you don't wish players to use as well.
You only missed, that the ArM5 p.81 Casting Score is just an input to the ArM5 p.81 Spontaneous Magic Casting Totals, which come up as either Casting Score/5 or (Casting Score + Stress Die)/2.
If I add a bonus to a Casting Total for Spontaneous Magic, I do so after the division by 2 or 5, while if I add the same bonus to the Score or directly to the roll, I do so before the division. And this makes a big difference.
Indeed. A character wanting to be great at sponts might do well to take Magic Foci and Merinita Charms. With the right materials at hand, casting totals above 10 are easy to obtain, with no stress die, even before considering Arts. (GMs will probably frown, though, and require spells cast thusly to take multiple rounds, though there's nothing in the rules about that.)