This place is great level 20+. Lots of stuff good for several levels, and only the snow imps and flurries aggro. You have to be prepared to get shot by high level enemy snipers, but you don't lose any xp or constitution, so it's alright.
You can't open the frontier keep door of a border keep if you aren't a member of that realm. Not only that, you can't attack the inside border door, it has no health.
You can not take a Frontier keep, just like you can't take a port-in, the person who said obviously has literally no clue about RvR. He's just making stuff up in his head. The guards at Port-in's and Frontier gates are all level 60 and they all hit for 700+ damage on a level 50 guy. Even if the whole server tried to take one, they would all die.
Whoever posted that Jordheim could be taken is COMPLETELY wrong. The only invaders who managed to get into the protected areas of the realms uses hacks to get in.
They *can* invade our mainland, it's happened before. Mythic has taken the question of PvP and made the game responsible for the switch. For the most part, if you don't go into the Frontier, you won't encounter PvP. But if the enemy DOES take all our forts they *can* enter the mainland. They can't enter our dungeons (which probably means they can't enter Jordheim) or bind here, but they *can* enter our mainland.
They've made the PvP switch a game mechanism instead of an intangible option that you turn on or off.
Let's not forget, the enemy can invade our mainland too, all they have to do is push through all of our outter keeps. Even Jordheim is capable of being taken.
Yes Frontier Zone are where RvR (Realm Vs Realm) Fighting will occur the fortreses in these realms need to be defended against attack from the other realms because they can be taken over by the other realms and then become thiers. By the same token we can invade Our enemies Frontier/Border Realms to take over thier fortresses.