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Thulsa’s Xoth campaign The Spider God’s Bride should fit right in. Also, individual scenarios from his Ancient Kingdoms: Mesopotamia would also have the right vibe IMO.
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Cyclopean Deeps is another one that comes to mind (comes in two volumes)
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Yeah; Cyclopean Deeps has come up before, but I'll add that it's the most interesting take on the Underdark that I've seen (Operation Unfathomable is decent, but a bit goofy) and seamlessly fits the Hyperborean setting. Hell, he's got Leng Spiders in there, which obviously I agree with.
And I didn't go back through the whole thread so I may have missed it, but Anomalous Sub-surface Environment would certainly work too.
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I think others have mentioned it above, or in another thread, but Gabor Csomos' The Lost Valley of Kishar is fantastic. Nice encounters, nice twists, my players managed to succeed accidentally and inadvertently in the subplot, which was really cool.