The Mother of Monsters is seen as a Dark God and the creator of all monsters. This is indead one of the aspects of The Mother of Monsters however she is also know as Lilith.
Prior to creating the Witches and finding redemtion Lilith had spent part of her existance as a demon it was then that she created many of the aberations and demons know today..
The Mother of Monsters is often seen as a massive writhing tentacled creature with a human-like torse and head at its centre.
She created the Maw and unleashed them on the Lavant as punishment to the original Lavant Kings who had become arrogant and capricious and destroy the evil socity they had created.