Claiming to be the son of Azog the Lesser, he lorded over most of the goblins and Orcs that had settled in Moria, though his authority was often times questioned by his bitter rivals: the Black Uruk chieftain Grishlug and the Deep-goblin Sorcerer Drisnak. To cement his power, Mazog arranged for a secret alliance with the darkness lurking in Dol Guldur.
Assisted by his allies, Mazog self-proclaimed himself King of Moria after the deaths of his adversaries and worked together with Dol Guldur throughout the War of the Ring. During ensuing skirmishes against the Dwarves and Elves of Lórien, Mazog was captured and ultimately found himself in the dungeons of Dol Guldur, as punishment for his failure to please the "Master" by maintaining control of Moria and the disgrace he brought to the line of Azog the Defiler. During the assault upon the fortress, Mazog was briefly freed only to be defeated permanently.
There are contradicting accounts on the ancestry of Mazog and its legitimacy. Some sources call him a son of Azog while others denote him as spawn of Azog's spawn. Attempts by this Wiki to remedy this have resulted in the identification of a second Azog, Azog the Lesser, grandson of Azog and father of Mazog.