What happens when an Aegis is cast around an exsisting Aegis? (second one is a larger area)
Cast by the same magi?
Cast by different magi?
Higher level than existing?
Lower level than existing?
The general consenses that we're leaning towards is that the 2nd one overlays the 1st but does not remove/supress it. So if you cast a higher level around the 1st it acts like the higher to anyone else.
If Mage B cast it around the original by Mage A. Aegis A is intact, but over layed with the new. So both mage A & B would suffer the aegis while in the center(A from Aegis B and vice versa), if magi B remained outside aegis A he would get the benefit of his aegis (B) while mage A would continue to suffer.
The other view is that the new aegis needs to penetrate the original, so Mage A(original) would be fine as long as he stays inside his Aegis, if he tried to leave he would have to pass through Aegis B and suffer.
Setting aside any Aegis that is keyed to an individual magus (from participation in the ritual or possession of a valid casting token), I'd simply apply the highest of those which remain. Even if you stay within a "friendly" Aegis, you'll still suffer from the "hostile" one that surrounds it. No need for penetration.
If the outer aegis is secondit would need to penetrate in order to effect tartets within the inner aegis. I don't think that the weird MR ignoreing nature of the aegis ritual will allow it to another penetrate aegis ritual with an insufficient penetration value.
If the inner aegis is cast second the casting odf the inner aegis would be hampered by the outer aegis while the spell is being cast.
I don't think that I would stack penalties from multiple aegises (aegii?). But just use the larger penalty.