A very interesting question indeed. On the answer I agree with you; things created with a Momentary Creo Ritual are in all regards mundane non-magical things. They may be more perfect versions of said things, being drawn as they do from the 'realm of ideas', but they are unmagical. In the words of RAW (p. 112) they "last as any other thing of that type". So no fuel no fire.
I could still think of reasons for Momentary CrIg rituals - to heal beings of fire (if you ever cross path with such a one... you unlucky sodales) or simply to light some kind of symbolic fire (could be used in a Mystery or in an Ancient Magical tradition or in the worship of some god). Finally you could make a CrIg ritual with duration year - and then it would presumably burn whether fueled or not...
Of course rather than creating a ritual you could make an enchanted device with a constant duration and thus create something akin to a permanent BoAF.
Which inspired the following (slightly off topic) image:
I imagine a flock of raven-shaped fires eternally flying about the abandoned tower of a Flambeau who died a decade ago. The lab lies undisturbed because everyone fears the defensive magic that the paranoid and powerful magus had to protect his sanctum. But until the lab is opened and the defenses disabled, a flock of burning birds, each hotter than any mortal fire, will continue to devour any who approach in a brutal conflagration.
The idea of a mage wandering about with a BoAF on stand-by, even for just a year, is more than mildly disconcerting from a Story Teller's point of view. Depending how it is defined/invented regarding control, and range, it could either be quite devastating to the game world, or a bit of a death-wish re the approval/tolerance of the Hermetic Order and other temporal authorities, or both.
Otoh, RAW, there's nothing really to stop it, but I'd think that, to be useful, it would have to either be a bit more complex than a simple BAF spell, or require other spells to wield it.
I certainly agree. My thoughts weren't toward the BoAF, but on fire in general and not so much damage and attacks. They thought of an ever-burning (for a year that is, if not making an item in place of ritual) brazier or some such is quite appealing in terms of scenes.
As a SG I would certainly shudder (and start to plot) if someone wanted a 'pet BoAF' following them for a year.
No - it would certainly be stopped by MR - if it is a mom CrIg ritual then it will only burn as a normal fire (granted there is something flamable nearby) and it cannot be used as a BoAF, or if it is a CrIg ritual with duration Year than it is most certianly magical - and thus resisted.
Really? Couldn't you create a unnaturally hot fire at a location with a Creo Ritual? Or a perfected fire from the plane of true forms that is hotter than a regular fire? What if you throw in a Muto requisite? I agree it would immediatly burn out.
What if you wanted to create a fire breathing shark? If you used the requisites and a Creo Ritual is this possiable to make permanent with a Creo ritual? Is it then "mundane"?
What if you want to make a crazy-made up animal (to Europeans), like a Turkey, Liger, or kangaroo, but otherwise mundane?
The fire is in all regards mundane, so I would say that such unnatural 'hotness' wouldn't last. In a Rego or some such thing it might be possible to argue that the fire would retain such properties.
I'd definately say it was magical and thus resisted by MR.
Interesting question. First off you would have to decide whether such areas not known to Mythic Europe exist or not, and then I'd guess you could easily rule it both ways (mundane or magical). But I would add that personally I would prefer not to have animals like kangaroos pop in our saga - no matter the motivation I feel it would kind of ruin any setting mood.
First of all it is a lot of time and vis spent to do the ritual - so that alone reduces it usefulness in overcoming someones MR. I most such situations where you have endless of time and no one acting against you, there are many other possible solutions.
Secondly if you purpose is to damage someone in the very round that the ritual is completed (as the fire would then diminish and die out) then you have to consider if it actually is magic in the very moment you conjure it and thus resisted. I cant atm envision whether ruling this one way or the other has any important repurcusion.
I would certainly rule that without fuel a CrIg ritual would burn out quickly. But here's a question, would a CrIg ritual to create natural fire at Arcane Connection range trigger MR? (Never mind the fact that if you have an arcane connection to a target you could use the penetration bonus to better effect... it's the theory that's interesting.)
A more cost-effective way would be copius use for rings. Most braziers are circluar, after all. Trace the top of it and you have a near perpetual flame at low level.
My magus does this when camping out. You don't have to worry about gathering fuel and to put it out you just smudge the ring in the dirt breaking it.
I hadn't meant to imply that the flames themselves are enchanted. I had envisioned a and that constantly produced a BoAF-like fire (or a crow of Abysmal flame).
As for enchanting a fire... you could enchant an item (say a turnip) to change itself into a fire and give it a constant duration, I think that it wouldn't burn out because it is at some level still a turnip.
this way you don't need to have a master fire crafter.
Back under 3rd ed, we had in Barcelona a group of Kabbalistic Jewish alchemists, who were established enough in their own right (and non-threatening) to both have their own "magical system" (undefined, but non-compatible with the OoH), and to have been given a "nod of approval" from the Order's usual monomanical "our way or the high way" attitude. (Also, they were just alchemists, and weren't about to bother anyone.)
But negotiating with them for pure elements and rare substances, and the variety of ideas for magical lab equipment and useful spells that sprung from those subplots was inspiring. Improbably hot forges, hammers, tongs, lenses, gloves to handle, examine and work the impossible materials that were worked therein, were all much fun.
(Slightly off topic, I guess, but tangents are a good thing sometimes.)