You can use a spontaneous fast cast spell (arm 83) to defend against another spell if you know the form of the spell. From the text, I am assuming the spontaneous spell does not need to penetrate.
I was interested in designing a formulaic spell that does the same thing ... and using spell mastery to allow fast casting. I am a little confused about how to do it (or if its possible).
My first thought was it would be either a perdo vim or rego vim.
Unravelling the fabric of form seems like it might do the trick. It obvious disrupts a spell that has already been cast before the spell duration is comlete. If fast cast, can it stop a spell before it takes effect?
Or would it have to be cast while the spell that is trying to be stopped is being cast ... and have to penetrate the spellcaster's parma?
What about rego vim. Rego vim can supress spells. Can you suppress or guard against a spell by fast casting a rego vim spell. If so, does the spell have to penetrate the spellcaster?
Or perhaps rego plus a form can protect against spells of that form?
I was originally thinking that if spontaneous magic can protect against spells without the need to penetrate, then there should be a formulaic spell that does the same. Perhaps the spontaneous spell works because it is specifically designed to foil the incoming spell ... and formulaic spells that do the same would be similiarly limited (they stop a specific spell and maybe spells similiar to it). Maybe it should not allowed for game balance.
Anyone care to offer a little guidance.
Another related question. If wind of mundane silence is given a duration ... will it continually blow away magic as its cast ... offering some protection. What about a rego vim room duration spell supression affect?
Here's a discussion we had on the issue a while back. Not surprisingly, when looking over the old discussion I found that I agreed much more strongly with my own opinions than I agreed with the opinions of others, so I advise you to give my words extra weight.
I think that unraveling the fabric of (form) would typically work.
In regards to your questions about rego (form spells) and so on, I think that for most spells you'd have to evaluate whether the fast cast defensive spell applies to the spell you are defending against. Rego ignem against cloak of flame? possibly yes, rego mentem against loss of but a moment's memory? probably no.
Fast casting to counter a spell- You are simply trying to take advantage of the fact you know what it is. By knowing what it is, you can alter it while its being cast...IIRC (Serf's Parma), once a spell is CAST, its not possible to alter it. So once that Pilum is on its way, its much more difficult to do something about it.
From the MuVi guidelines (ArM5 p.159) one can derive that affecting a spell being cast with another spell requires either Fast Casting, or cooperation between the two casters.
Spells you are casting are not protected by your Parma, however: they are neither a person, nor clothing, nor items. (See ArM5 p. 85 on what is protected by Parma.)
Yes, this works against low magnitude spells. But the fast-cast spell would not have to overcome the other caster's Parma.
You probably mean a D:Conc or D:Diameter PeVi spell with T:Room. Yes such a spell would provide some protection against low magnitude spells. Which are those a desperate magus would cast at a sodalis, if he needs to breach his Parma. As you wish to cast it at your surroundings, make sure to invent it in a way not affecting Parmae - or you might bring your own Parma down.
Are you sure about spells being cast not being covered by Parma Berengar?
I reasonably certain they are (serfs parma). In fact i'm sure its in the Muto Vim guidelines when it talks about altering a spell being cast by a foe.
The reason i'm sure about this is my own character has master a muto vim spell that changes another spells target. My aim is to use it against silly flambeau who try to immolate me. As they cast pilum of fire or ball of Abyssal Flame, i cast my muto vim spell and change the target from me, to them. My magus has learnt the fast casting and penetration abilities for this spell.
Can anyone with the book to hand confirm whether i'm daydreaming or if that bit is there in the MuVi guidelines.
The Muto Vim guidelines say that: you can only cast these spells on formulaic magic and that you have to be able to fast cast your MuVi spell, and you will be needing to look at your Penetration Score of the MuVi spell - but not to penetrate the other casters Parma (at least it does not say so, but nor does it exclude house ruling it), instead you have to compare it with the Penetration of the spell you are trying to target.
So now - go back to daydreaming, while I confirm how high pentration is a must for all us respectable Flambeau!!!
On a sidenote - since the rules say that all spells cast by a magus that are not Personal range have to penetrate, would it be possible to decide to house rule that all spells with a personal range are thus cast within the parma - and thus another intervening magus has to penetrate the parma in these instances to affect the targeted spell?
In any regard this links to ones generel idea of what magic is. Is it some force from within the magus or is the power drawn from the suroundings? This is important for deciding what does or does not happen whitin your MR when you cast spells.
