A bit different from ablative parma rules of the past, this variant is a pure improvement (in the sense of improving Parma , not necessarily in the sense of improvingthe rules):
Parma works exactly the same as now, with the following exceptions:
Parma as we know it stays up all the time. It does not go down at sunrise or sunset, is not a constant effect that can be dispelled, but acts exactly like normal Magic Resistance.
When a magus casts his parma ritual, he gets a number of automatic MR successes equal to his score in Parma, not cumulative. When his MR would normally fail, an automatic success is consumed instead. A successful attempt to dispel Parma Magica would normally dispel all remaining successes, except that it is thwarted by a single automatic success, as usual. No part of this ability pertains to parma that is extended to another person: Successful penetration cannot be thwarted and therefore does not consume a charge.
So, PM 1 lets a newly gauntleted magus automatically resist one magical effect. PM4+2 lets him resist 6; if he extends his Parma to other people, MR is calculated as though his score were lower, but he still has 6 auto-resists that only apply to him.
I'm always in favour of making Parma stronger!
Just one question: if it does not "go down", how can you renew it (in particular renew the "autosuccesses")? Do you need to manually dispel it with Perdo Vim?
No more than the canonical version of Parma. (IE, no. RAW, there isn't a difference between being subjected to a single magical effect for a season or a year and always being subject to one magical effect, though not necessarily the same casting or even same effect. So a magus under the influence of Parma except for a few minutes per day would incur Warping if Parma did that.)