Silver Discs of Elaran
From The Griffin's Crier
Ancient discs scribed by an aquatic elf who's tribe did battle with the odd half-human, half-fish followers of Ylerys long ago. They defeated the cult, and slew the demon, sealing its body in five urns. They buried these urns in the undersea ruins of the demon's temple.
The Discs close with a warning that the seals will not last for all time, and that a handful of cultists fled during the final battle.