Tower of the Toad Lord

From the introduction: In the days of the Nul Empire, Alvir Staemore (the Blade King) set upon a campaign to ensure that the full moon of Skalvirn would always shine upon his kingdom. This included invading the Fenlands of Orastrier. There on the remote moors, the Watchtower of Gulvest was erected and, after the death of Alvir, forgotten.