Access by the Burun Fortress, after killing the Fortress Barrier. Walk through the "stone", which acts like a portal (but does not show up as such on the radar).
Message on entering the dungeon: You steel your nerve and resolve and take a step toward the vile-smelling mound. You look beneath the pile and spy an entrance. Drawing your last ounce of courage and try to plunge below.
Killing the Ruuk Fiend Watcher will reduce the spawns around Morgluuk in the central mound dungeon.
As the Fiend dies, it lets out a vicious sound. It's ward is unprotected, Morgluuk will send his personal guard of savages to investigate. This will weaken his lair.