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.
The SW mound is a breeding ground for the Burun and contains many Burun Eggs. One of the eggs has very high points and destroying it will reduce Morgluuk's hit points by 50%. It can be found on level -6 (see map) in the SW corner.
The egg explodes violently. A shrill sound reverberates off of the halls, Morgluuk is howling in pain. This egg may have contained his offspring! He has become weaker!