Beregar is a dwarven settlement introduced in the Update 8.4. It's located under the islands of Fenrock and Mistrock. According to Emperor Rehal, the city originally was formed by two tribes, but one of them left and founded the city that is now known as Kazordoon. There are three wooden mailboxes in the city, all to the west of the great hall. Near Beregar you can find the Beregar Mines and the beregar bonelord cave, among other hunting places.
To reach the city you must enter the caves of Fenrock, descend two levels and use a pick on a crack located southeast of the tortoise cave. After that there's a long path from which it's possible to reach Dragons, Dragon Lords, Diabolic Imps, Liches and other strong creatures, but these are isolated from the main path so the only thing you'll meet on the way there are Skeletons, Rotworms and Goblins of all kinds. After you reach the city for the first time you'll then be able to use ore wagons to skip this part of the voyage, and you'll have started The Hidden City of Beregar Quest.
Knights: A decent level and with good skills are highly recomennded for these creatures. A level 20+ with 60/60 and with a knight set and dragon shield can kill one of these on defensive fighting, but will lose half of their health, if not healing. A level 45 with 75/75 would be able to kill these with little waste, although 85/85 is the ideal skill range. You might want GFB or Berserk in case you become surrounded by these.