Lord of the Rings Online - Monster Play Overview @ Official Site

An overview of Monster Play , the PvP equivalent in Turbine's upcoming Lord of the Rings Online, is available at the official site.

LOTRO offers a unique form of player vs. player combat known as monster play. Players are transported to the Ettenmoors, a consensual PvMP (Player vs. Monster Player) region about the size of the Shire. Here, the Free Peoples and the forces of Angmar are in constant active conflict, and players can choose to join the fight as either their normal Free Peoples character, or as one of the servants of the Enemy!