
gbonehead Owner - House of Books and Games LLC |

Not sure how soon you need it, but there's this. There's a few modules, etc. that I know of that use devils, but that's the only demon-related one that I know of off the top of my head.
However you might want to check out the Savage Tide campaign in the later issues of The Dungeon, as well; that's pretty heavy on demons.

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Witchwar Legacy is for 17th Level characters and, while not heavily Abyss-focused, does feature giants serving the Demon Lord Kostchtchie and involves obtaining (with the potential to later go destroy) an artifact related to him. You could probably edit it with low effort to lessen the emphasis of some of the witch/Baba Yaga focus and concentrate on the Kostchtchie parts.