The angels were created as servants of the gods in order to implement the Creation, yet they themselves were forbidden to interfere with the evolution of the human race.  When Lucifer--the highest angel in service to the higher god Jehovah--learned of a great and nebulous time of strife which would befall mankind unless the angels brought gifts of enlightenment to the mortals, he and his cohorts exercised their free will and violated divine mandate, knowing that there would be retribution yet  choosing their love of humanity over their love of divinity regardless of such consequences.
    One-third of the angels sided with Lucifer in this act and continued to side with him during the ensuing Rebellion and the War of Wrath.  They had dared to question divine will, and for that the rebel angels who survived the war against the holy Host  were rounded up by the Host to be sentenced and cast down.  And the Abyss was crafted from the Void to serve as their prison until the end of time.  Only Lucifer was spared from this torment, sentenced as he was to wander the mortal world and slumber beneath it, apart from all the angels he had knowingly led to their doom.
    The Abyss is nigh-absolute darkness and nothingness.  Magic and the powers of supernature fail here, and the senses of those who enter the Abyss are greatly numbed, if not entirely removed.  It was in this manner that the fallen angels dwelled for thousands of years, with only each other and their own thoughts and regrets for company.  Some grew detached from what they once were and succumbed to monstrosity beneath the burdens of so much omnipresent torment, and predatory heirarchies were soon established among the Fallen.
    Now the Abyss lies shattered, struck asunder by the Sixth Great Maelstrom, the great cosmic storm which spilled forth from the Shadowlands and into the Void.  Many of the Fallen have been liberated by this storm and have found their ways back to Earth, the seat of Creation.  While some of these fallen angels have endured their age-old torments remarkably well, it is the threat posed by the Monstrous among them which causes the Host concern and might very well cast the throngs of humanity into dread and panic if they knew of such an ominous event.
There is presently no map of Abyss.  Is it even possible to commit such nothingness to a map?
to The Cabal
to the Omniverse.