Spontaneous magic shouldn't be a logistical exercise of marshaling resources (your Arts, Stamina, other situational bonuses) in order to determine what you can do. I enjoy games about logistics, I do not particularly enjoy the effort related to spontaneous magic. Not everyone is going to be good with math. And while what I presented in the OP, does ostensibly require someone to multiply by 5 (to convert magnitude to level), most people can do that quickly, as the 5s are one of the easiest multiplication facts to learn.
I'd like a system that treats Spontaneous Magic as having no penetration, but allows vis for boosting penetration, because you're basically feeding the energy from the base spell from yourself, and then channeling the power of raw vis through you into the spell, too. The hail-mary is over-rated.
I disagree with the premise that using vis shouldn't be without risk because it's using a player's resource. Players can be convinced to use their resources in many ways, some games see players get swindled out of their resources, that's using a resource for a negative outcome. In Ars Magica, the only resource that should be used to affect a certain outcome is Confidence. Someone buys that +1 vorpal sword only to find out it isn't, or something, you've now created a story about hunting down the shifty merchant. If you use vis you should be risking some kind of negative outcome, because vis, as we've been taught by the book is pure condensed magic and it should be treated carefully. Perhaps it is onerous in my OP to make it rolling botch dice, and you need to check for botch first, but the choice to use vis is the players, and the risks are clearly communicated.
As mentioned, to me it was purely a mental exercise - I like the current rules for spontaneous magic - but I was trying to simplify as much as possible.
In this light, sacrificing the "hail mary"* spont was fine.
A potentially larger problem exists if we use Christian's model as written, in the case of very low-level effects with fairly high Arts.
with Arts around 10, stamina 0 and no significant aura, to spont a level 10 effect it makes little difference (as Christian shows above).
But with Arts around 20, stamina 3 and a magic aura of 3, casting a levle 5 effect, penetration ability 0, we have:
Traditional: (46+stressdice)/2 is about 26, or about penetration 21 once we subtract "spell level" of the effect.
Christian's Model: 46+stressdice is about 52, or about penetration 42 once we subtract twice the "spell level" of the effect.
Either way, it's easily doable without fatigue, but penetration will be atrocious.
I had to look this term up, it was not familiar to me.
I agree that the two of us and our group do not need to change Spont magic, and are merely letting ideas and analysis (what's plural for this?) fly.
For ease of play ruling that Spont=Pen 0 seems ok.
As for Hail Mary, obviously you are not a football fan...but haven't you ever played Blood Bowl?
I still think this is not needed. We went from too complicated, to something almost simple, to wild mutations of the structure.
I like it the way it is. But if you insist, here is a simple and effective idea...
Easy Sponts: Just use one Art score, the lowest one, and nothing else. No roll or division or any other bonuses (except maybe the Aura). This means that a magus can pretty much cast any spell of that Art which is that level or lower at will.
Sponts with Effort: by spending a Fatigue level (or something), you get to add Stamina and a die roll to your lowest Art. You get other bonuses too, but still only one Art. The lowest one.
Formulaic Spells: Use the full formula with both Arts. Roll a stress die if stressed and a no botch stress die if calm, as if it were mastered (mastered spells always use no botch dice now). No Fatigue for low totals, just failure. And everyone can now optionally spend a Fatigue to add +5 per level spent (and may opt to do so after the roll, like Confidence).
Bam. Simple, no on the fly math needed, and each style of casting get's its due. Mastered spells can now never botch, which solves the Aegis issue some may have (as in the odds and number of potential annual Aegis Botches is greatly reduced, since it may be presumed they are always cast by those who have mastered it).
You're not the first one to suggest the single Art model, not even in this thread. As Tugdal points out a few posts later, this is always strictly weaker than the current model.
Worse, it doesn't really solve what is probably the central problem:
Is there a faster, simpler way to design spells/effect levels, or do we accept that only those players who bothered to read the books, get to use spontaneous magic?
I think having a simpler method, such as marko's, for casting spont spells would quicken the design as you could at a glance tell what your upper limit is as opposed to having to calculate it for every combination; it may be weaker but more usable, also remember that virtues like diedne magic and life-linked have yet to be considered so will need to be tweaked and may provide that extra power; alternatively maybe things like fast casting might be easier to do.
on another point, Ars Magica is generally a long running game, over many many sessions and while I don't expect my players to have read everything, I do expect them to know how their character works, not even off by heart but with a familiarity, e.g. a Mentum magus should have a good sense of the Mentum guide lines.
I did not invent it. I just simplified another idea. I like the current way though, and think that most gamer mentality gamers will read the book and or figure it out themselves quickly. This has been my experience. The easy-breezy style gamers must rely on the advice of the sg and other players, and gamers of that style are usually cool with it.
As for the simple system, in both cases it is more powerful. Easy sponts use a whole Art score as compared to a total divided by five. Fatigue sponts don't divide the added bonuses such as shouting or talisman attunment.
Those with Diedne Magic would get to use both Arts in their formula.
Life Linked & Life Boost would each add +5 per fatigue level.
My issue with this simple system, besides that I find it useless and therefore hate it, my issue is that it lessens the gap between Sponaneous and Formulaic magic.
