Is the following a valid scope for minor magical focus? Is it to wide?
Including: Creating, modifing or weakening/destroying wards, innate MR, Parma or Aegis. Directly affecting Might-based MR, Parma or Aegis. Any defensive magics which actively protect the warded target (like CWoP or SotIS)
Excluding: Affecting any direct physical protection like armor, cover, skin/hide/scales. Penetrating existing MR for effects not affecting MR directly. Magic that gives Soak by changing (Muto-ing) the target's skin/hide/fur/scales.
"Wards" is a canonical Minor Magical Focus, but people also consider it about as broad as you can possibly go since it is close to 1/10 of Rego. Then you're adding in PM, AotH, and other MR. So I would expect most troupes not to accept this as a Minor Magical Focus, pushing it to Major.
My problem was that Major Magical Foci are Protection or Defense. Which are so broad that nearly anything can be pushed into them. MMF Damage is a canonical example from the CRB and it is also so wide that it can cover half of all the Forms. But it gives a clear guideline on its scope.
So how would you dissect/divide the focus described in my original question to get 2 or 3 separate, minor magical foci?
I don't know as it would divide beautifully into 3 Minors. Certainly, we have "wards." You could go with "magic resistance" as one, since AotH says it protects like PM that would seem to cover all the MR, PM, and Aegis stuff. It's that third group that is hard to turn into a single Minor. I could see something like "warning" covering half and "barriers" (don't like it, but haven't come up with a better one yet) covering the other half.
The real problem here is that proposed Focus is not focused. It's a Focus on All The Things, which is easly to clue in on because there's no succinct summary of what is covered.
I think it might even be broader than MMF on Magical Defenses; I probably wouldn't let someone apply their Focus to destroying magical defenses any more than I'd let someone apply their Healing Focus to effects that make it necessary for someone to be healed.
If you want to be good at all those things, I'd take a MMF in Magical Defenses, then add some Potent Magic virtues to cover what that misses.
Since it covers ANY type of Magical Defense I see 3 Minor ones here... Create, Modify & Destroy Magical Defenses, separately, could be seen as a Minor Focus each one.
Either you reduce the type of Magical Defenses that it covers, or choose a single Verb
I have to concur that, as stated, it's too wide for a Minor Focus. What makes it too wide (and somewhat ill-defined) in my view is the ability to boost the creation of virtually every magical defense across every Form and Technique, from Circling Winds of Protection to Wizard's Sidestep. This is broader than the canonical Major Magical Focus "Damage", which only covers a specific subset of magical attacks produced by the magus (those causing direct damage).
I think I would allow as a Minor Focus something like ... "Meta-Defensive Magic", that would cover the strengthening, disguise, detection, dispelling, modification etc. of any supernatural effect of a defensive nature brought into being from some other source. This is essentially a subset of Vim that, while potentially involving any Technique, can target less that 1/5th of all the Form.