I've played and ran a few games of Ars Magica and am likely to run another game sometime soon. However I think I'd like make some house rules to simplify things a little and would appreciate peoples opinions, experience or suggestions.
For example Spell Mastery. It feels fiddly, I understand it (I think) but to me it feels like a level too much detail. I'd prefer mages inventing new spells or creating items rather than working on mastery. Are there any hidden downsides to me just removing it as an option?
(I also definitely need to re read the warping rules and penetration as most of my experience was with 4e - first read makes warping sound a little too limiting on the level of magic I like)
I have never really found any of my characters investing heavily in spell mastery. You get better bang for your buck by making an item. Maybe one level of spell mastery is useful for specific spells (i.e. a paranoid maga might take "spell resistance" mastery for Intangible tunnel, or fast cast for leap of homecoming), but the quadratic XP curve soon makes it very expensive.
There's a couple of impacts on the game. You would essentially be killing the main option to specialize in a spell rather than specialize in a type of magic. Casting subtly and fast-casting (mostly for defense) relies a lot on spell mastery as well. So is the ability to crowd control without a group spell. It may lead to magus specializing more in parma magica (for defense they might otherwise use a fast-casting mastered spell), in finesse attacks (because parma magica is more important and because you lose the capacity to master a spell for penetration) as well as ironically learning to fight, because relying on a fast-cast dodge to get out from a sword's path without spell mastery is that much more of a gamble. I don't think you're fundamentally breaking the game, but I wonder why you're looking at removing spell mastery to simplify the game, considering it's not a skill anyone is forced to invest in.
Removing Spell Mastery could work but it would actually remove a great many options and require some rework of a few Virtues. Several of the Spell Masteries allow reproducing the effect of a Virtue for that single (or all levels of a general) spell.
One of the big things it kills is a Magus having "Favored Spells", including builds which focus on having few spells which can manipulated by the skill of the Magus to perform a broad range of functions. Magic users who have very few spells but use them in creative ways is a standard in fiction (my personal fav is Skeeve from Myth) and an enjoyable play style.
One important feature of Spell Mastery is that it reduces the chances of a Botch. This is especially important on ritual spells, which can be incredibly dangerous to cast for any Magus who is not built to reduce the chance of a spell botch happening.
In my simplified-for-beginners box set version of Ars Magica, I cut Spell Mastery, along with many other things (group combat, exertion, reputation, specializations, ceremonial magic, fast-casting, experimenting in the lab, and a lot more). But I would never cut Spell Mastery from my ongoing campaign, because it’s just so damn useful for both GMs and players.
Spell Mastery allows players to distinguish themselves from each other even when they know the same spells. Plenty of wizards know Rusted Decay of the Ten Score Years for example, but a wizard who can fast-cast it, one who has increased Magic Resistance towards it, or one who can cast it 3 times in one round all feel different and unique. You want players to invent new spells; Mastering a spell can make it feel like a whole new spell!
Mastery allows me to simulate things we see wizards do in movies and literature. In the Harry Potter films, wizards shoot bolts from their wands like a rapid firing pistol! A player wants to do that. How can they, in Ars Magica? There’s only one way: get Spell Mastery (multicast) on that pilum of fire.
You don’t like Spell Mastery? That’s cool, don’t use it. But unless you need to radically simplify the game for everyone, leave it in the game for players that find it fun.
Consider the impact for the Aegis of the Hearth. Without spell mastery to eliminate the risk of botch, casting it yearly is dangerous.
I don't like the multicasting option, and have effectively removed it from my games.
On warping, Twilight is complicated and not very meaningful in my opinion. You could eliminate it entirely and leave just the general rules for Warping, i.e. acquiring Virtues and Flaws (perhaps at a simpler rate, e.g. 1 Flaw for the first level of Warping, and then alternating Virtue/Flaw per 2 more Warping). Even if you choose to keep Twilight, you could simplify its mechanics, perhaps e.g. making any magus that double-botches a spell casting gain (Magnitude) Warping Points and roll for Twilight as a (Sta + Enigmatic Wisdom - Magnitude) roll, gaining a Virtue/Flaw based on the roll (in addition to normal Warping effects) and being removed from the scene. Incidentally, I totally recommend overriding the "time in twilight" chart, or removing it entirely, to make time-spent-in-twilgiht better serve your saga.
On penetration - it's a bit hard to simplify, but consider that the game often reduces to "I penetrate with ease" or "I don't penetrate at all". So one option is to forgo the idea that weaker-spells penetrate more easily, and just have penetration = spell roll. This greatly simplifies the gameflow, as you don't need to subtrat the spell level. You'd need to up the Magic Resistance numbers to fit, but I recommend doing that anyway (otherwise Magic Resistance is pretty much irrelevant). Using this system you ostensibly lose the whole shtick of using low-level but high-penetration spells, but I'm not sure this works thematically and in my expeirnec it affects the game only fairly rarely.
As many others here, most PCs I have seen ignore mastery completely. Thus, I rarely need to know the rules. When it does come up, it really rests on the player to make sure they know the rules. You can play for a long time without it every coming up. If it comes up, it is because it is important for the story or one of the characters therein.
To me, simplification is more about limiting the total number of rulesets the troupe actually uses. It matters less which rulesets they avoid. This is particularly clear if you consider allowing the many supplements with special rules for special concepts, including RoPx4, HoHx3, LoM, C&G, A&A, etc. If each character picks up its own optional rulesets, one has a lot of work. Spell mastery, like the optional supplements, is one of these rulesets which matters a lot to some character concepts, and hardly at all for the majority. It boils down to whether you want those concepts in your story.
Twilight and certamen are other core rulesets which rarely come up in game. Twilight is different from the others though, in that twilight concerns every magus. I don't disagree that you can probably simplify it away without harm to your story, but IMO twilight has a meaning which is very present in the magus' mind. Removing it changes the setting. Removing mastery does not change the setting, it just removes the magi who have cared for mastery from the story.
From this conversation so far, I'm gathering that ArM5 treats spell mastery much as described in The Mysteries for ArM 4. Is that by default or are you all including ArM5's version of TM in your discussion?
Spell mastery is much simpler in the core rules of ArM4. One could use it like that in their saga for simplicity's sake and then only have to deal with the more "specialized masteries" if someone actually gets their magus initiated into those Mysteries in play.
I also prefer the Penetration = Casting Roll over the aforementioned Penetration total - Spell level. Casting roll = penetration is the ArM4 default on this, I believe.
@Snowy, why not just continue to use ArM4 if you have experience with it already? It still works fine and as a bonus any player who doesn't have a copy can still get the core PDF free from Atlas. Our Troupe is using it as the basis for our modern Urban Fantasy saga and having a lot of fun with it.
It's a good point. Some friends sold me on the idea that various things gabs been improved for 5e, parma and merits/flaws or boons & hooks in particular. I've read through that once but need to digest the changes in more detail.
As other people have said, removing Spell Mastery will not hurt the game as a whole. Many characters never pick up Spell Mastery anyway and still do just fine.
It will remove several options for mages and hurt some character concepts though.
Changing the rules for penetration or warping would need to be considered far more carefully though, since any changes there have a very high risk of changing the balance of the game. Depending on the changes made and depending on what kind of game you want this may or may not be a problem.
Mastery by core, has changed a lot in 5ed. I never read 4ed mysteries so I do not know if that is the same. I have never seen a 5ed mystery for improved mastery, but I can't say I have read the Mysteries in full.
The consequence of that is that Parma be almost worthless. Every high-powered spell needs a large casting total, and therefore gets a huge penetration, and only the very mature magi who have put an effort into param would be able to resist. I could never understand, in 3/4ed, why parma could have been so important for the founding of the order, when it is so feeble, and 5ed solved that problem for me.
Oh? I still find verisimilitude hard here. Consider a specialist with, say, 20 in Te and Fo and a relevant Magical Focus; this amounts to a spell casting total of perhaps (72 6 die + 3 sta +20 Te +20 Fo + 20 Focus + 3 aura); let's add Penetration 3 for 75. He can cast a BoAF (level 35) with Penetration 40. Assuming his enemy has Fo 10 (not a significant expert in this domain), one needs Parma 6 to resist. This is pretty high. If the caster takes the effort to invest raw vis, he can push his penetration by +40, which would require Parma 14 (!) to resist. And he can use other tricks to up his Penetration, like arcane and sympathetic connections, various Virtues, a talisman, whatever.
And we haven't gotten to the true grand masters of the Order, with Arts nearing 40.
I find that Parma and indeed Magic Resistance in general doesn't quite work, numbers-wise. In my current saga I use a combination of doubling all spell levels, and doubling Magic Resistance.
If casting total = penetration, then every fight between magus will end with a single high-powered spell, because there's no incentive to cast a weaker spell hoping it will go through Parma when your killing blow will do the job. And killing blow are also incidentally harder to defend against with spontaneous defense. So the fight between master magi ends with the initiative roll, assuming they know at least one spell that can defeat an opponent.
At the top end, arguably true, however, 5th ed at least makes parma relevant for a long time. The example given requires 420 XP, and a focus. That's not trivial.
The old model of penetration being casting total, well, we are saying Flambeau couldn't get a casting total more than 5 times Bonisagus' parma which seems odd. Because resistance wasn't a thing before Bonisagus, on a story level it's fair to say a magi always went for the biggest spell in their repertoire. On that basis Flambeau's fire spell bouncing makes senses.
Let me put it this way - your incentive to use the level 20 pilum of fire instead of the level 35 ball of abysmal flame is that the latter fails to penetrate, but the former does. So the stats need to fall within the small window of 15 points, for this to occur. It can happen, but I'd suggest that very often you'd be outside that window.
So if you're looking for a place to simplify, without it having ramifications throughout the ruleset, I think that's a fair way to go. You'd be losing that tactical consideration when it applies, yes.
"At the top end, arguably true, however, 5th ed at least makes parma relevant for a long time. The example given requires 420 XP, and a focus. That's not trivial."
My experience has been that magi's Parma tends to stay around 1, so it doesn't work. The cost of increasing it, especially past level 2, is just very high, and not worth the benefit. Reaching Parma 6 above, for example, would have required 280 XP, that's quite a lot, and players just want to invest their XP into being able to do something, rather than be resistant to some things. YMMV.
Except that it's very easy to generate a high lab total for the purpose of learning spells you can barely cast. I just pulled up a current character. My best lab total, with experimentation, in the right aura, at the right time of the year gets to 60. My casting total, at an inopportune time, outside of a magical aura, falls to 30 in my best art combination. So a spell I develop in a single season without a lab text will be cast at 0 penetration by RAW, unless I use vis + have a beneficial aura (which may increase the opponent's MR anyway... not useful) + work on getting an arcane connection. With two seasons, or a season with a lab text, I can learn a level 40 spell that I can cast at -10 penetration by RAW, but which in your rule, I would cast at +30. With that tweak, anyone with an offensive magical focus would single shot most non-master magi and anything that's not a dragon right outside the gauntlet. Pilum of Fire wouldn't ever be used, when there are more overpowered effects like lightning and the ball of abysmal flame, or just Perdo Corpus die. The RAW is why magi don't learn mastery-level offensive spells from their mentor usually. They are useless except against mundanes. It's also why Demon's Eternal Oblivion is often learned at level 10, for example, and not level 40 which would single-shot most demons. Do you imagine how paranoid a magus outside of gauntlet with his Parma 1 and his average art at 5 would be? My guess is he would shelter in his laboratory and come out when he has Parma 8 + 20 in all forms.
That's exactly the tactics I developed as a player under 3/4ed. Parma was not worth the bother, as I would have to raise it to at least 4 to have much chance even against a starting character¹. Under 5ed I see players -not only myself- taking puissant parma and whatnot. The bracket of 15 points that you are talking about is actually pretty large for young and inexperienced magi.
I agree that it may change for for mature magi. When the casting total reaches 75 or 100, 15 pts difference is not such a big deal.
¹ Of course, Wizard's Grimoire made it even worse, with the charms against magic effectively outperforming the parma, but that's a different matter.
Although in 5e, when you start talking about mature magi (at least, ones who expect to be fighting other magi) there also starts being the possibility of them having the Magic Resistance mastery against common attack spells, at which point Parma 6 and 10 Form resistance can defend against +80 penetration again.