You can teleport to an enemy realm's coastal keeps (including it's merchant keep) if you have a valid supply line to it.
You can only teleport to your Realm's inner keeps and it's merchant keep, and only if you have a valid supply line to it.
While standing near the stone, with the Realm War Map displayed, you can teleport to any keep with a white disk beneath it. You can use these portals by right-clicking on them, which brings up the Realm War Map. Once you have entered the frontier, you can move between keeps your Realm controls with the aid of the Frontier Portal Stones. Snowdonia Fortress and Castle Sauvage grant access to Albion characters, Vindsaul Faste and Svasud Faste grant access to Midgard characters, and Druim Cain and Druim Ligen allow access to Hibernian characters. You can enter the Frontier area by passing through one of your Realm's Border Keeps.
Each realm has frontier areas where the land is wild and your enemies may attempt an invasion (and you, in turn, may attempt to invade them).
