This is one of those YMMV moments. I find it much easier to do a little mental arithmetic than have to remember an arbitrary rule.
Note that the calculation could be done in advance for all spell levels and degrees of enhancement and presented as a table -- no mental arithmetic at all then.
Random? It's about as deterministic as things can get ... but I assume you meant "arbitrary", rather than "random"? The system I sketched out is really no more arbitrary than any other mechanic in a game of this sort, and has the enormous benefit of being simple and concise. I do understand, though, that some people of a less than mathematical bent will turn off as soon as they see it, and to them it will always be a strange dark secret akin to working out VAT on a calculator with no percent key ...
Eh? ArM rounds all spell levels up to the next power of five to determine magnitude. There's rounding everywhere. I didn't suggest any more than that.
I didn't really get involved in this little discussion with the intention of changing anything. I did it to explain what it is in the rules that I find makes them needlessly difficult to grasp, to use, and to remember; and I've tried to show how a different rule would obviate what I see as unnecessary clumsiness in the RAW.
I don't much like House Rules. I like to stick to RAW wherever possible, or throw out the mechanics altogether and invent new ones, but this is one area where I might consider a simplification. At present I'm a player, not a story guide, but my time will doubtless come.
Put me down as one who finds it a real stretch to believe that there is an underlying problem.
There is a easy to use, elegant general rule: 1 magnitude is 5 levels. This rule has a single exception: it changes below level 5.'
If you want something simpler, I don't at all advocate your crazy"base level* a constant" plan. It would be a mess in play and a pain in the ass to explain. Players would be screaming "needless complexity".
Instead go back to the system used in the first three editions: All spell levels are decided by the storyguide. The spells in the book serve as examples. When a player wants to make a new spell they talk to whoever is the appropriate sztoryguide and say,"the new spell looks like a bigger deal than this spell but less difficult than this other spell. We'll make it level 30'
No rules, no confusion
You're joking! You can't compute 15*1.25^4 in your head? 
I did point out that 1.25 is very nearly 2^(1/3), ...
so 1.25^4 is about 21.25 which is 2.5...
and 152.5 is 37.5 ...
which ArM will want you to round up to 40 so you can call it Magnitude 8.
Well, 15*1.25^4 is actually 36.6, but that's near enough.
As I commented elsewhere, you could do all this with a table if you're a table-oriented kind of a being.
It's easy to use and elegant up to the point at which there is an exception.
There are actually two exceptions:
- It changes below 5
- It changes above 50
The first problem here is that there is no one point in the book at which that simple statement is made. It's important, it needs to be stated simply and clearly in a place that everyone can find quickly.
The second problem here is that the mechanic is a crock. That matters less, but that's what I was discussing in the post to which you replied.
What could possibly be simpler than:You can extend the Range, Duration and Target of a spell, if you want to do this you must add 25%, cumulatively, to the level of the spell for each step by which you extend it.
There is only one thing to remember, there is only one thing to work out, it doesn't need and explanation, it speaks for itself.
Note that I'm not putting this forward as a new wonder mechanic that eliminates at a stroke all the shortcomings of the RAW and cures the common cold, I'm giving it as an example of a mechanic that avoids the one flaw that particularly bugs me in the rule we're discussing. I know it doesn't give quite the same answers, I know it has different behaviour at boundary conditions, and I'm sure it has shortcomings elsewhere. I don't expect everyone to like it (particularly not those for whom arithmetic is a foreign language). It's just an example to show how a different mechanic might not suffer from the need for arbitrary exceptions.
I take it that "sztoryguide" is term peculiar to sagas of the Transylvanian Covenant 
Yes, of course, I would expect the storyguide to play a part in setting the level and effect of a new spell ... and the RAW are there to guide the SG too (very important for relatively inexperienced SGs -- everyone has to start somewhere). I don't think it particularly matters how easy the rules are for the design of new formulaic spells, but for spontaneous spells it is very important not to interrupt the story for a full-blown debate about which rule on which page applies in each case.
Having all the relevant rules written down in one place for ease of reference is essential, as is having rules that can be simply stated and have general applicability.
It doesn't change above 50
Page 114 under "Changing Ranges Durations and Targets"
Honestly 1 magnitude = 5 levels is simpler to do, simpler to explain, and it deals with arithmetic growth rather than geometric which is IMHO preferable.
The exception : --that when you're dealing with levels lower than 5 adding and subtracting sets of five breaks the system--- is pretty much an obvious part of the system. I've never had problems explaining it to a new player. Of course just because you're the only one that I've heard of having an issue with it doesn't mean that there aren't other folks out there with the same difficulty.
The tone of my post may come across as more antagonistic than I intended. No belligerence was meant. I just haven't yet found a way to put my head in a place where I can see the present rule as confusing or complicated.
It does change above 50 (for some values of "it"). For formulaic and spontaneous magic "one magnitude equals five levels" effectively becomes "one magnitude is an infinite number of levels", because at 50 you can no longer increase magnitude just by increasing levels, and you have to switch to ritual magic.
That's an arbitrary change that has to exist because if you could carry on boosting the power of formulaic magic at five levels per magnitude mages would get too powerful. The problem is that the flat "one magnitude equals five levels" rule breaks down (becomes too cheap) for high levels of spell.
A different rule that inherently made higher magnitudes of spell more expensive (in levels) wouldn't need to be capped in that way. The capping is only necessary to balance the game because the underlying rule is broken (as it is for very low levels).
Yes, thank you, I know where it is. It's buried in a paragraph of text (and you have to read the example as well as the rule statement to understand what it means). It is important. It could be -- and it deserves to be -- stated more clearly, and in a box so that it hit you in the face as soon as you looked at that section.
Note, also, that if you look at "Magnitude" in the index it takes you to P111, where there is a statement of the "one magnitude equals five levels" rule with a note that for first magnitude spells things "work differently" and a reference to P114. Nobody I know who looked at the words "work differently" understood them to mean "this is an exception to the rule we have just stated, so do go on and look it up".
Also, FWIW, if you look up "Range", "Duration" or "Target" in the index you get a list of five or so page numbers for each (including P114, which is good). In each case a couple of these pages are FAR more important references than the others, it would have been good to see them highlighted in bold.
It's not that the mechanic (in this case) is actually difficult to comprehend. I'm sure I'd have used it without a second thought if I'd actually found it in the book when I was looking, but having not found it I started thinking harder about it than I really needed to so that when I did find it I was in a mood to be critical of the mechanic.
I agree that it's easier to repeatedly add 5 than to repeatedly multiply by 1.25 -- not by much, if you're any good at mental arithmetic, but it is easier.
However, I disagree that "one magnitude equals five levels, except when you start from less then five in which case one magnitude equals one level until you get to five, and you can't go past 50 at all" is any easier a concept than "one magnitude equals a 25% increase; no exceptions, but you'll find the increase gets very steep once the level gets high".
No worries. I didn't read any antagonism into your posting ... but I've been wondering how to get your head into a position from which you can see from a different perspective and at least understand the point I'm making, if not actually agree with me. (I thought "severed, on top of a pike", but that seemed rather harsh, and unlikely to help anyone ).
No, the rule is not "complicated" in an absolute sense, it just irritates because it could be simpler. I don't think the rule itself is "confusing", it's just that I found its statement in the book -- when I eventually did find it -- to be poorly worded. Maybe I'm lazy, but I don't expect having fun to be so much work.
Yes indeed, Erik. I whole heartedly agree.
All I suggested was a mathematically "smoother" mechanic for those who were asking for it. Personally, I like doing little arithmatic problems, but a lot of folks don't and would much rather wing it than calculate it.
I think this system (the RAW) strikes a very good middle ground, keeps it very simple (count by one until you hit level five and then count by fives thereafter), allows for little spells for almost every magus but keeps the big juju for the devout specialist. Great stuff.
The in-game rationale is up to each of us to come up with (assuming we have to at all), but the one that makes the most sense to me is that there indeed are points in the natural world where there is a "break point." Things below that point are very easy, things above it are suddenly and substantially more complex but still possible. The elastic limits in metals would translate well into a fictional mideval magical setting.
No consistency.
For those that like to wing it, I suppose this works, and has, for a long time. Me? As a relatively new player (5th ed., only),this smells too much of other fantasy RPG systems with weaker magic systems. Could I play in this environment and enjoy myself? Sure. And I have. But I much prefer the portability and consitency that the current 5th ed. RAW.
Just remember: count by ones until level 5, count by fives thereafter. Simple and easily done on the fly even by the less arithmetically inclined.
Best,
-K!
Wow, and I thought I was a bit picky over some of the rules. 1-5, increases are 1 at a a time. Over 5 increases are 5 at a time. Ritual if over 50. If I were to try to HR anything, THAT wouldn't be it. I really doubt there's a simple way to improve it, and i'm not convinced it needs to be improved.
In any case, I suspect 1-5 is what see's most use in play, it's the easiest to spontaneous. 6+ is more likely to be a formulaic spell that the mage is inventing over a season, and the SG has more time to think it over.
Well, each of us can have a opposite opinion about the rules and we can't disagree.
The fact is, theses are the rules, and by my experience, theses work well.
If you don't like the rules you can say it, but don't complain about them, most of us like them that way. 
If you really don't want to use theses rules, well there is two possibilities:
- There is much good Roleplaying games out there, choose one you like the rules and play it.
- Tweak the rules as you feel like, thoses rules are suggestions by all means.
I can assure you, they are not broken, hacky, mathematicly-challenging or unbelieveable to me. And, they work quite well in game too.
The fact that spells above level fifty need to be rituals is not a break in the system for determining levels. levels for spells above fifty are calculated in precisely the same way as levels below fifty.
The ritual / no ritual distinction is about feel and mood, not level calculation. A character who casts a mighty spell to destroy a mountain should darn well do it with a 4 hour ritual incorporating the destructive essence of the venomous viper of the Baltic sea and the crystalline heart of Lord Grom king and grandfather of ten-thousand earth spirits. Not just by casting a spell in a single round.
If you calculated levels differently you'd still have to decide what was and what wasn't a ritual .
It isn't about magi being too powerful, it is about effects and causes matching up.
.. unless you're a verditius.. then they'll laugh at you as they wave their mighty rod of mountain smashing, proudly exclaiming how they can still do that 23 more times today.
And people laugh cause they need to use tools to cast spells.. really ^^
You'd have to do such a table for every spell level from 1 to about 40, and would need it everytime you spont.
This'd give one of those big rolemaster-like tables, and you would have a hard time remembering it:
1 -> 2
2 -> 3
3 -> 4
4 -> 5
5 -> 7
6 -> 8
7 -> 9
...
Moreso, you would have even more than now to had 1 magnitude at a time: Level 3 + 5 mag would mean 3 -> 4 -> 5 -> 7 -> 9 -> 12...
If you want a table, the 1-2-3-4-5-10-15-20-25... is way more simple, and easier to remember IMO: Once your level is above 5, just add 5 levels per additional magnitude.
Three shall be the number of the counting and the number of the counting shall be three. Four shalt thou not count, neither shalt thou count two, excepting that thou then proceedeth to three. Five is right out.
That's a matter of perspective ... for formulaic and spontaneous casting there is a discontinuity at 50 because you can't exceed that level at all.
I hate discontinuities like that. I hate it when the mechanics interrupt the smooth passing of the story.
I agree entirely about mood. The rules point one in the right direction, I just don't think they do it very elegantly.
Well, it's ritual if you have to wear a frock and do the crystalline heart thing, at the Dark of the Moon, it's an ordinary spell if you just wave your arms around and shout. The difference (with different mechanics) might be that the ritual gives a bonus on casting without which the spell might not be within a given magus's ability.
It's about balance. Everything is about balance. The balance in play (which is about magi being too powerful), and the balance between the plausibility of the game world and the complexity of the system (higher complexity can lead to more convincing simulation of the fantasy world, but brings more mechanics that distract from the narrative).
Ars Magica tries very hard to get the balances right. A game whose main narrative thrust centres on the lives of power-crazed and increasingly unstable wizards in a basically low-tech and unsophisticated society has a fairly hard act to pull off, and ArM does better than any other I know of (and I've played a few) without seeming unbalanced. An adventure game in which most of the key characters spend most of their time not adventuring, but heads-down in the lab or the library, while being an excellent example to students has an even harder act to pull off, and ArM manages that brilliantly (I put it down to grogs being pooled, which is definitely an idea that ArM originated).
This game does so much so well that it is all the more disappointing when occasional rough edges in the bare mechanics draw attention to themselves, and drag one kicking and screaming out of the saga.
I had in mind a 2-dimensional table with base effect levels on one axis and steps of augmentation on the other. That would have about 20 rows of about 12 columns, and would be good for every spell you'd ever cast.
That is: there are three augmentations (Range, Duration, and Target) and each can be increased by only about 4 steps, so you only need 12 columns. There are only a limited number of base effects used in the RAW, 1,2,3,4,5,10,15,20, .... Say that's 1..5 and then every 5 to 75 gives 20 rows. One sheet of paper, easy. If you need other base effects you can interpolate.
And remember that you would only need the table if you couldn't do the mental arithmetic (and I expect most players would end up knowing the most common results anyway).
I hate Prolemaster, mostly because of the endless stupid tables. I think ICE invented lots or arbitrary tables on purpose just to increase sales of photocopiers^Wthe rule books. I only suggested one table, and then only for those who can't hack the arithmetic. Who uses the Resistance Table in RuneQuest, for example, and who just says "My roll divided by five plus my POW minus your POW is more than 10, so I succeeded"?
No, absolutely not, you'd just count the number of steps (the RAW calls them magnitudes) you wanted to add to the spell's effect and look in the appropriate column, in the row for the base level for the effect. Either that or you'd quickly learn that 5 magnitudes was a factor of just over 3, and 3 times just over 3 is just over 9 which rounds up to 10. You can worry about the odd +/-1 after you roll the dice.
I don't want a table at all, that suggestion was just to please the people who can't or won't accept a little multiplication.
What I don't like is the fact that augmenting a spell of level 4 - or, for that matter, a spell of level 20 - from "Individual" to "Touch" adds 25% to the level, but making the same augmentation on a spell of level 5 doubles the level. It defies plausibility. It feels wrong.
If you don't like multiplication you could do something like this: To augment a spell by one step, increase its level by its current total magnitude. So, to increase a level 4 spell from "Ind" to "Touch" would add 1 to the level, to similarly increase a level 5 spell would add 2, and to increase a level 20 spell would add 4. That probably makes augmentation of mid-level spells a little too easy and the actual numbers might need tweaking, but you get the idea. With this scheme you really would need to compute the level costs for the increments one at a time, but the mental arithmetic requires only addition, and you could still have a single table to summarize the overall results.
HAHAHAHAHAHAHAHAHA
OK, I think we've saturation here. Me, I'll stick with the RAW. Others can spend the time finding new mechanics and guidelines. I wanna play!
(Geeze, Monty Python. Can't get away from them...)
-K!