no imunities for PC's is great, however NPC's and even some creatures DO need it. we can't have players destroying a faction every 5 minuites, guards are supposed to be truely powerful, the PC's back them up.. but that doesn't mean the guards are supposed to be weak, leaves the door wide open for a faction to get griefed by somone just because the faction has no high levels on atm.
i'd say each guard should be atleast CR 30+ and ofcourse given imunity to alot of things, including issacs. make them require a melee and mage to kill, not just some hopped up mage. should take an army to invade another faction, not a mage and too much free time.
You've Got To be Kidding Me
Maybe guards could start out rather weak at the outer parts of a faction's territory (scouts) and get stronger towards the capital. This way, when players walk around a little bit exploring enemy territory thet wouldn't be wasted by the first scout they meet, but advancing towards the enemies bastions becomes more and more difficult.
Not sure if that's already the case, to my low-level character they all looked "impossible".

Not sure if that's already the case, to my low-level character they all looked "impossible".

I have opinions of my own, strong opinions - but I don't always agree with them!