No, I don't mean making magical armor or removing aging points by sluffing off your skin.
I'm talking about the way in Hermetic effects scale. In the RAW one magnitude increases the size of a target by a factor of ten. It doesn't take long to blow up to such a size as is hard to fit in a realistic Europe. What if instead we were to double the size with each magnitude? Five magnitudes, something often achievable, would create 32x volume instead of 100000x. You'd no longer have to worry about Magi creating as much gold as the Spanish took from the New World in three centuries.
Would it ruin spells and abilities near and dear to the hearts of players? Is it a good or a bad thing that Magi can create cathedrals? Should it be applied to all Techniques or just Creo? I would not want to apply it to Intellego, myself.
One problem with this is the application of Group. You'll be better off using a Group spell to affect a large target.
One should also consider affecting giants, dragons, and so on. The mix-up of two size mehcanics makes this difficult, but current RAW is that +1 magnitude allows +3 Size, so you can affect a small dragon (+7 size) with two extra magnitudes (base is +1 Size). This is about 100-fold factor in mass. Under your system, that would require adding 10 extra magnitudes. So, Cripple the Howling Wolf PeCo 25 becomes Cripple the Small Dragon at level 35 under RAW, but at level 75 (i.e. a powerful ritual) under your system. In other words - your rules make it impossible for magi to fight massive opponents, like giants or dragons.
That said, I agree that magi can affect and create too much too easily.
Edit: Oops, that's 100-fold for +7 magnitudes under your system, but that's still level 60 which is too high.
At the risk of really annoying people, I think the real root of the problem is the current editions attempt to "clarify" targets like group and individual. Back in the day, a group was "that identifiable group of things/people over there". An individual was "one thing". Issues like a giant vs a human, or an army vs a few knights, or the West-midlands vs a field, were left up to common sense or stoyguide fiat. A spell to create a cathedral was higher magnitude because the stroyguide/troupe felt it should be.
In creating clearly defined guidelines for such things 5th edition cleared up one kind of "at the table" debate but, as this post (and IMO many, many others) clearly illustrates, opened up an entirely different can of worms. My solution, such as it is, is a return to vague old days when Hermetic magic was a little less well defined, but a lot more magical.
That's a good point. We don't want to take away the ability to affect bigger targets. Maybe spells could continue to affect +1 size per magnitude on living targets, under the justification that you're not really targeting all of the creature.
This would also deal with the issue YR7 raised. Creo is the biggest problem for me, probably because most effects are done at duration Mom. Add in +3 for Moon and overly large effects become less practical. Maybe an even simpler alternative would be to make permanent creation take a +5 duration. But I still have issues with massive Rego and Perdo, especially after seeing the flying castle in Legends of Hermes, apparently done with a ReTe 33 effect.
In general I agree with you that the system is overly mechanical and in the process has lost something. The Boundary target is now defined so tightly as to be pointless at standard size. But on the specific issue, I think you still need a sense of the magnitude of the material a Magus can work with, be it +1x, 2x, or 10x with each magnitude.
I´ve experimented using *3 as the size modifier, moving Group one Magnitude up and adding "Few"(a group with no more than 3 individuals) at +2 as a lesser version of Group.
It messes up some spells and guidelines pretty badly but it also works very nicely with other parts of the system so...
I would like to use it, but i haven´t found a good way to fix the things that gets broken by the change.
Unfortunately it´s several years since i tried it out so i simply dont remember...
I just know i ran into some problems once you got down to details. I still considered it playable right away though so i´m fairly sure it wasn´t anything gamebreaking.
Anyway, for clarification, i used that 3 in such a way that 33, ie. 2 Magnitudes equaled *10, that makes for a relatively simple system:
And so on. It also makes it easy to compare to the original as you need exactly twice as many Magnitudes to raise the size the same amount.