MALGOTH, THE:
A "terrible entity" that ruled over several layers of the Abyss eons ago, he was finally defeated by a consortium of seven demon lords (Antisif the Befouler, Cyndshyra of the Seven Torments, Felex'ja the Tiger King, Ixinix the Lord of Blackwater, Qij-na the Shattered, Rhindor'zt the Black Prince, and Wejindhastala the Tempest), who led a fantastic assault on his haunted realm. The victorious demons scattered the Malgoth's essence across the Abyss, only to be deposed and ultimately destroyed by underlings on their home layers.
Sources:
Dungeon #117 - "Touch of the Abyss"
Fiendish Codex I: Armies of the Abyss
Dragon #357 - "Gazing Into the Abyss"
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