Sludge Beast

Sludge Beast is a level 17 rare mob sludge beast ooze found in the sludge of the Sludge Fen in the Barrens. It is on a 4-6 hour respawn timer.

Unlike most rare mobs, the Sludge Beast is known to drop 2-3 random green items per kill.

Background
These strange creatures share an elemental heritage, but have been corrupted by the powers of chaos. Now they exist as tortured masses of semi-sapient goo. No one knows what their motivations are or if there is any specific ecology behind their existence.