flawed parma, what is divided by two?

Games Discussion Ars Magica
1

Hi,
Let's says magi A, B, C and D have a parma magica 5 (corpus) and 20 in corpus

Magus A is normal , his parma against corpus is (5+1)*5+20 = 50.
Magus B has limited MR corpus => (5+1)*5+20-20 = 30
Magus C has flawed parma corpus => (5+1)*5/2+20 = 35
Magus D has both flaws, his parma corpus is thus (5+1)*5/2+20-20 = 15.
My doubts are about "flawed parma magica" because I read the MR from the definitive now and it has been very long time since I read that in the core from 2004 and I never took the flawed parma magica flaw.

I thought (apparently wrongly) that it would divide the (parma + form) by two, but DE is quite clear that you add form resistance and parma resistance, and flawed only divide the parma magic resistance by two:
"Parma Magica adds Magic Resistance equal to five times the maga's score in the Ability to the resistance based on her Forms"
Since I'm still not using the flaw but designed my sheet-tool around the rule, I need to be sure to change what I wrote previously.

Thanks for confirmation.

I tried to search for a topic since I did think it would have a clarification but either there is none, either I didn't find one (because most results appear from play-by-post campaigns on these forums)

2

I thought the bonus from form was the form bonus, ie divide by 5 rounded up. So corpus 20 is a 4 MR

3

For that question, ArM5(DE) has a clear answer (I think it was so in core too): "Hermetic magi have a base Magic Resistance equal to their score in the Form most applicable to the spell cast."
The "form bonus" is only used for other things (soak, rolls).

But as for my question about the flawed parma flaw, you play it like I posted in example?

4

We will agree to disagree on is it 20 or 4, as I think later sentences clarify it is the form bonus.

To answer your question. I agree with how you've applied the maths, even though I would use 4, not 20.

5

The Form Bonus is only for Soak. For MR, you add the score of the Form to the (Parma magica * 5)

6

I read them like this:
"Your Parma Magica provides only half the normal Magic Resistance [it grants]"
PM (corpus) is 5+1, yielding 30 MR. Half is 15.

Moreover, if Corpus yield 0, the "normal Magic Resistance" is 30 + 0 = 30. This has the same result. It seems you'd have to weave both Flaws to get an alternate result.

In a way, the original example has a flaw, the "+ 20 - 20" is trying to cancel the Flaw-free calculation. "You gain no bonus from one of your Form scores" doesn't say to remove the Form score, but to set it to zero.

Thus, the example becomes:

Magus A is normal , his parma against corpus is (5+1)*5 + 20 = 50.
Magus B has limited MR corpus => (5+1)*5 + 0 = 30
Magus C has flawed parma corpus => (5+1)*5/2 + 20 = 35
Magus D has both flaws, his parma corpus is thus (5+1)*5/2 + 0 = 15.

Had the "divide by 2" for magus D becomes distributive: {(5+1)*5 + 0}/2 = 15.

7

Okay, so no magus C with 25 MR corpus, that's fine; a day with a learning moment is always a good day. (Well it was yesterday, but still appliable!)