I'm not concerned about all Hell breaking loose, but that a PART of Hell will break loose ... it'll be much harder to detect.
Hell is a celestial realm that serves as the home of Lucifer and his demons, and is also the place where humans go after they die if they have achieved their Fate. It is the farthest place to be found from Heaven in the entire Symphony, a perpetual flat note trying to drown out the grace of God.
Each Demon Prince has a place in Hell where their will holds sway, known as a Principality. As with the Cathedrals of the Archangels, these can vary widely: Saminga rules from a bone citidel, Vapula has turned the realm of Tartarus into his personal laboratory and several of the more "fleshly" Princes such as Andrealphus, Haagenti and Kobal have sites in the legendary city of wickedness known as Shal-Mari. The Hearts of demons who serve a Prince are kept in the Principality, usually under careful watch.
Unlike Heaven, where blessed human souls celebrate and serve, in Hell, the damned souls are simply cattle to be stripped for their Essence. Some Princes torture souls for it (such as Belial with his lake of fire, or Vapula with his experiments) while others find it more entertaining to let humans bargain it away for a cheap thrill, giving up their most precious possession for a moment of degredation.
The Lower HellsEdit
In theory, any demon can descend into the Lower Hells. In practice, few do unless summoned. The Lower Hells are the personal domain of Lucifer, and even Princes hesitate to catch his eye uninvited. Those that have been there and returned comment on the horror and the soul-chilling cold.
A Touch of HeavenEdit
While Infernal Interventions have no power in Heaven, Divine Interventions can still reach into Hell. In addition, two powerful angels, the Angels of Final Judgment, stand watch outside Hell's gates, to make sure that no soul goes to Hell by mistake.
An angel in Hell doesn't automatically sound a celestial alarm, but will quickly draw enemy attention, since there is no way to conceal what the being truly is. Such interlopers, if captured, may well be brought before Lucifer himself to satisfy his curiosity before the "entertainment" begins.