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). You can enter the Frontier area by passing through one of your Realm's Border Keeps. 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.
Once you have entered the frontier, you can move between keeps your Realm controls with the aid of the Frontier Portal Stones. You can use these portals by right-clicking on them, which brings up the Realm War Map. 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 only teleport to your Realm's inner keeps and it's merchant keep, and only if you have a valid supply line to it. You can teleport to an enemy realm's coastal keeps (including it's merchant keep) if you have a valid supply line to it.
If you do not have a valid supply line to an enemy frontier, you must either swim there (which will take a long time), travel by fast boats on a pre-designated route, or purchase a player-controllable boat. The latter two options can be accomplished at any of the four docks located in your frontier. These docks can be found near either of your relic gates, or at either of your Realm's island keeps. At docks in your realm, you will find a dockmaster who will sell tickets for both pre-route boat rides, and player-controlled boats. The dockmasters found in enemy realms will be hostile towards you, and will not sell to you.
If you do meet members of an enemy Realm within your frontier area, you will not be able to converse with them, nor they with you. They are invaders, and you must repel them, if you can.
These temples, found behind impassable walls set with massive gates, are the home to each Realm's most treasured relics. These relics, when captured by an enemy, will provide significant bonuses to everyone of that Realm. However, capturing the relic is no easy task. To access the relic temple, the invaders must first capture the corresponding keeps that will open the relic wall's gates. They must then fight through any defenders, and the powerful NPC relic guards at the temple, and stand upon the plate corresponding to the relic, until the relic lowers to the ground and is able to be picked up.
These impassable boundaries are marked on your Realm War Map as a thick red line, cutting off the relic temple from the rest of the Frontiers. The gates to these relic walls can only be raised by capturing the keeps associated with them.
The border keeps, mentioned above, are a safe area with access to a Realm hastener, to grant you limited short-term movement enhancements, a frontier portal stone, and a merchant to purchase siege supplies from. The area is protected from invaders by a number of very powerful Realm guards, but once you travel away from it, you'll be without their assistance.
Across the river from each relic temple is a relic town. These areas have class trainers, a number of merchants, and their own frontier portal stone. Note that, while you can teleport from a relic town, you cannot teleport to one. If you attempt to log in to the frontiers into a keep or tower that is no longer controlled by your realm, you will automatically placed at the closest relic town.
Keeps are important structures located throughout each Realm's Frontier. Which keeps you own will determine where you can teleport in the frontiers, and the Realm with the most keeps will have access to Darkness Falls, a popular dungeon.
Each keep has four towers associated with it. If any one of those towers is captured by an enemy realm, it will disable the ability to teleport to the keep associated with it.
Keeps and towers can be claimed by any guild of the realm the controls it. Each guild can only claim one tower or keep at a time. Ownership of a keep or tower costs the guild Guild Bounty Points, which are granted whenever a member of the guild kills a member of an enemy realm. Both keeps and towers can be upgraded, increasing the strength of it's walls and doors, the power of it's guards, and the number of hookpoints available, as well as increasing the actual height of walls, the inner keep or (in the case of towers) the tower itself. A claimed keep or tower will also report to all members of a guild when a guard at the tower is killed, stating the number of enemy players in the area. Members of the guild will also be notified when the keep or tower is under siege.
All keeps and towers will show flames around them on the Realm War Map whenever it becomes significantly damaged. The more keeps a realm owns, the longer it will take for flames to appear.