I've had an alarming thought about how Aegis of the Hearth affects magi. I'm hoping that I'm delusional again, but I would like some reassurance either way.
Assuming that Aegis must penetrate Magic Resistance to have an effect (much as Wards do).
If an Aegis fails to penetrate a foreign magus's Parma Magica (which is Order of Hermes-brand Magic Resistance), is he affected? If he casts a spell, does it still suffer a penalty of half the Spell Level?
For example: a 25th level Aegis is cast with a penetration total of 20. If a foreign maga enters the Aegis with a Vim MR of 27, and thus the Aegis fails to penetrate, does she suffer a -13 penalty on her spell-casting, or no?