Mother of oblivion
Vast monstrosities that lurk beneath the deepest darkest waters, mothers of oblivion are some of the most fearsome servants of Lamashtu. Though rare, these creatures are rightly feared by most sentient humanoids as they represent the antithesis of civilization.
Bearing a head like a plesiosaur atop a thrashing mass of tentacles and eyes, Black Magga is an immense creature indeed. Although she is effectively immortal until slain, she has spent many of her years in deep hibernation. These slumbers could last for a dozen centuries or more at a time, and are punctuated by relatively short periods of activity that generally last for only a few decades. These long periods of sleep have had something of a debilitating effect, for with each century of slumber, she grows weaker. She is now but a shadow of her original power. That she remains as powerful as she does today speaks volumes to the terrible wrath she must have possessed at one time.
The party fought Black Magga during the flooding of Turtleback Ferry. They were very lucky that the monster retreated back into the water when it did.