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Who is responsible for the Abyssal Geysers?
The way it was described ('group content') made me think of Dolmens, which made me think of the Daedric alliance trio - Nocturnal, Mephala, and Clavicus Vile. But the picture with it looks like crustacean monsters:
...and that suggests to me it's the Maormer and/or the Sload.