The ring of trial is often simply called the Nagrand Arena.
It is located in Nagrand and can be entered in the game world, causing the player to be flagged for Free For All pvp, allowing even same facton players to kill each other while within it.
It is also one of the 5 current possible location for Arena battle.
The ring of trial is better known for its 4 pillars, which allow players to break line of sigh with each other (often called 'pillar humping'). Most strategic element about this arena involve using the pillars in some fashion, or preventing your opponents from using those same pillars.
Like all Arenas, after 5 minutes, 2 Shadow Sight power ups will appear on the side of the arena. When a player touch the power up, he gets a debuff that greatly increase his stealth detection but also increase all damage taken by 5% for several seconds.