Note I was not "defending" my initial proposal. I have myself said I'm not that happy with it.
I do feel however that:
a) as written, Premonitions should be able to "warn you" of an impending, dangerous botch.
b) there is some way to fine-tune it so it's balanced (I was providing Charmed life as a reference).
I agree that due to the practical impossibility of predicting botches(I would personally want to avoid pre-rolling) there should be a way to prevent or reduce them with premonitions.
Maybe something to the tune of "If you botch, you can spend a confidence point to see if the premonitions would have warned you. If they do, you did not do the action that would have botched".
Potentially change the paying of confidence to after the roll if that proves to be too costly.
This does add a layer of mechanical back-tracking that I personally don't find too elegant, but you would need a wiser man than me to find a method that has no backtracking nor pre-rolling every single check.
The closest ability to what you want is probably Threads of Fate from Rival Magic (pg 100 - 101). That has abilities like "roll a die and put it in front of you - that's going to be the result of your next stress die" (EF 6 + simple die) and "reroll a failed or botched roll" (EF 18 + simple die).
You can take it if you're not a Muspelli, but you're going to struggle to meet a lot of the EFs without the casting total benefits they can get.There are also some significant limitations on how often you can use it (at best you're getting a handful of uses a scene, but it might be per adventure).
There's also the Tueor Fortunem guidelines Learned Magicians can access (reroll Ability rolls up to a certain EF), but those require you to be a Learned Magician.
True. Apart from my suggestion in post 3, and that was not about botches, I've just been saying it's unbalanced.
Let's try to provide a balanced suggestion of how premonitions could mechanically work.
When a zero is rolled, prior to rolling botch dice, make a premonition check. The difficulty of the premonition check is 1 higher per extra botch dice. If the check is successful, the player can choose to cancel their action. They can do nothing else in the turn. They can choose to finish the action and roll the botch dice.
For many formulaic spells, a zero, the spell would still be cast, so it is a question of is it worth losing the turn?
The reason for the extra difficulty. Only a complete loon, or someone desperate, is casting lots of spells in a botch heavy area. Level 3 faerie regio. 6 extra botch dice? No thanks. Premonition guy just casts, knowing premonitions will save them once they have got the premonitions skill to a decent level.
To justify the extra difficulty in story. The whole place is ringing with danger when casting magic. It's really hard to pick out if this was the specific spell that went wrong.
In my mind, a magic botch is purely down to character action, with no premonitionable bad circumstances to explain it. After all, everybody knows that there are powerful forces in the faerie regio, and if you mess up, you provoke them. You do not need premonitions to know that. Hence, I do not think that premonition should alter your risk perception as far as spell casting is concerned. The combat example is harder to dismiss from my mind.
This goes down to the question of how premonitions work. Is it a vague sense of unease if one is approaching a risky situation? Is it more a "spidey sense"?
When I approach a rickety rope bridge, I don't need premonitions to know I could fall through a rotten plank. Same with casting in a faerie regio. I know it is risky. If premonitions just gives a warning of ambushes, that seems a bit weak.
On a practical level, a botched spell, something went wrong in the world the magi is in. Just like someone on the rickety bridge stepping on the wrong plank and falling, the magi grabbed for something in the magical realm and missed it, causing the botch.
If we think the dodgy plank on the bridge is something that could trip premonitions, then I'd argue a botch could trip premonitions as well. If we accept that,the next question is game balance.
I went about it the other way around. My guts tell me that botches are off-limit for the sake of game balance, and then I strive to interpret botching post hoc to make this a narrative necessity. That does not mean that I consider alternative narratives to be impossible or implausible, just that I find them less supportive of the game I think we desire.
So I do agree that there is a plausible narrative where the rotten plank could trigger premonitions. I do not agree a priori that that's the narrative we would want. I certainly argue that it is only one out of many plausible narratives.
Just being nitpicky.
We know that no Hermetic divination can break the Limit of Time.
We suspect The Creator doesn't let anyone see the pre-ordained future, just hints.
I am under the impression that Premonitions will warn you you are going to get into a dangerous sword-fight, but not a blow by blow description with commentary.
We also know that even Divine Powers can at best give a hard to understand prophetic vision concerning future events. And that's when you essentially ask God directly.
Nothing else in the published Ars Magica material can even come close to telling what will happen, only what is likely to happen based on the current situation.
The aforementioned Threads of Fate ability to see the result of your next stress die roll?
Why not (with a sufficiently good roll)?
We seem to agree that Premonitions will give you a warning when you are about to step into a mudhole and spalsh your nice dress with mud; it should just warn you that if you walk down a medieval road, you might get dirty.
But if that's the case, Premonitions should give you a warning when you are about to step into a mudhole as you try do dodge an opponent's swordblow in a fight - all the more, because it's a more dangerous situation.
How long does a Premonition take?
I would rule if it takes a round, you get a round of information, or a synopsis that will fit into a round.
A Premonition that your sword will break during a fight with Sir Snapsalot is hard pressed to give you enough information to recognise which sword strike is exactly the fatal one beforehand.
And if you are concentrating on the Premonition during battle, you would be adding botch die to your melee combat.
I think I agree with the general consensus that Premonitions (as well as Divination IMO ) won't be able to warn against botch (also it'd be a bit gamey and also hard as we're rolling dice here).
However, as an "evil" SG, I'd probably let a gamey player who want to do it make the attempt. Roll one or a couple (roughly the expected rolls being Premonitioned) and if ANY of them scores a 0 the answer is yes (no second roll of botch dice, and magic botch being two "0"s). Character still attempting the action would then later not get the roll but automatic botch. Also, the norns really don't like people trying to "trick" fate, so actions to avoid it may risk same botch regardless.
Looking too closely at the future can be more dangerous than not to.
Another approach could be to make a bunch of rolls (in a row) and keep them, until actions take place at which time they are assigned as they were rolled. Player will know in advance which roll goes were. I wouldn't use it myself, but I've seen it done in other games.
That, or being a Weird Ex Miscelllanea (shameless plug)