In the southern reaches of the Barrow-downs lies the Great Barrow, Othrongroth, one of the oldest and largest of the Edain mounds. As the Witch-king's power has grown, fell spirits have taken possession of the rotting remains of the dead in his name. What was once a sacred place of solemnity is now the home to evil lurking in the shadows.

The details are as below:

In the southern reaches of the Barrow-downs lies the Great Barrow, Othrongroth, one of the oldest and largest of the Edain mounds. For many years the Dunedain of Cardolan protected it, until a great sickness arose from the south. This plague devastated Cardolan, leaving the ancient burial-mounds vulnerable to the horrors of the Enemy.

The Witch-king of Angmar sent fell spirits from Angmar and Rhudaur to inhabit the Barrow-downs and turn them into a place of great terror. Taking possession of the rotting remains of the dead, the spirits became barrow-wights, the chief of whom sits in lordship in Othrongroth at the command of the Witch-king. As the Shadows in the East and in the North stir once again, the wights of the Great Barrow arise and stalk the Barrow-downs in service to their master.

Othrongroth was created by the developers at Turbine as the first public dungeon instance to be visited by players. In Book 1 of the Epic Story, a terrible assembly of the Witch-king with other evil servants of Sauron sets in motion the events that will shape The Lord of the Rings Online: Shadow of Angmar.