when do magical focii apply?

I have managed to get myself confused again.
I can't quite recall or find the ruling for the following sort of situation:

Assume that the mage Amagus has a Minor Magical Focus in Familiars.
I understand that the focus applies when casting a spell specifically designed to affect Familiars. But what happens if Amagus casts a generic Animal spell on an an animal that happens to be a Familiar?

Which of the 3 applies?
a) gets no Focus bonus, because the spell is not specifically about Familiars.
b) gets the focus bonus only if he knows he is casting on a Familiar.
c) gets the focus bonus whether or not he knows the target is a Familiar.

The above example can change the wording from "Familiar" to "dogs" (both focus and target)

I would say C but then I think “Familiars” is a pretty trash focus and doesn’t really provide a clear example of this situation.

Canines/Dogs can provide a better one. Someone casts The Beast Remade on a dog to turn them into a human, you cast a Corpus spell on them not knowing they are actually a dog and the focus should apply because the target is a dog.

Familiars was the first mMF I thought of.
Then I realised canines apply as well,

The essential aspect of the hypothetical is that the spell is not restricted/dedicated to the mMF, and the target of the spell may not be recognised (for whatever reason) by the caster as part of the mMF.

I'd say C. You get the focus bonus if the target is within the scope of the focus.
However, to get the focus bonus when inventing the spell, the spell would have to apply specifically to the focus.

So, assuming you have a focus in Canines:
The focus would apply when casting Beast of Outlandish Size on a wolf, but it would not apply when inventing the spell since the spell can be used on any kind of animal.
For the spell Shape of the Woodland Prowler however the focus would apply both to casting and inventing the spell since it specifically deals with wolf form.


I need to stop posting while exhausted.
Now that I am a bit rested I recall thinking option c) with mMF in Familiars was a cheap way to scry on magi. I can't seem to recall the line of logic that reached that conclusion.

Of course, nothing prevents you from inventing a spell "Wolf of Outlandish Size" - like "Beast ..." but restricted to Wolves - on which you'd benefit from the Focus.

Also, I thought that "Familiars" was a Major Focus, as per HoH:MC p.89? I agree that Minor would make more sense, so I checked the errata, but found nothing there.

By the way, I would vote for c) too.

I would say c) lets say the character has a focus in canines and hears an animal within the bushes, sees the bushes moves, and casts a voice range spell to put the animal to sleep. The focus would apply if the animal was a wolf or dog, regardless of the caster being aware of its nature.