The Price of Generosity
This massive rift into the depths of the next plane opened in a previous age when the Diabolist managed to get some of her most powerful fiends to tear through the walls of the world. Demons poured out through the Abyss until the Great Gold Wyrm fought his way to the bottom of the Abyssal rift and sealed the gate with his body. His presence now keeps the greatest fiends from entering the world. Lesser fiends who can sometimes slip in through smaller cracks remain trapped in the Abyss by the Wyrm’s magic rather than by his physical presence. Occasionally a demon breaks through the Great Gold Wyrm’s magic or a wizard or sorcerer summons one out. The Abyss is two hundred miles long, between one and five miles wide, and reaches down into Hell itself.