How to get the Mace of Molag Bal - Elder Scrolls: Morrowind
Video: How to get Mace of Molag Bal
The Mace of Molag Bal is rewarded to you for completing Molag Bal's Quest, given to you by the Statue of Molag Bal in Yansirramus. You can find Yansirramus west of Sadrith Mora, it's on one of the larger islands that is close to the central landmass. Interact with the statue of Molag Bal inside and you'll be tasked with finding the dungeon of Kora-Dur and killing the Daedroth Menta Na inside.
You can find Kora-Dur to the northeast of Maar Gan near the dungeon of Kogoruhn which you'll visit during the game's story. The entrance to the dungeon of Kora-Dur is locked with a lock level of 95 but assuming you kept the Menta Na's Key you were given you can open it no problem.
Kora-Dur is a rather linear dungeon with two routes to Menta Na. There is a more direct route that you can follow through the underwater tunnels or you can go the indirect route across solid land. Even if you don't have underwater breathing you can probably still travel through the tunnels without fear of drowning.
Either way, once you're done with this quest return to Yansirramrus and interact with the statue of Molag Bal again to receive your mace.