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Fiendslair is one of the Towers of the Fiendlorn constructed to serve experiments toward immortality conducted by Mesandroth Fiendlorn. Related to Fiendlorn's experiments with reverse possession of a demon and forms of controlled undeath, it was sealed and abandoned after the assistant tasked with its maintenance, Eledwyn, attempted and failed to betray Fiendlorn.1 It is located in the Umbral Basin northeast of Ridwan.2

An expedition to Fiendslair in 4714 AR, involving agents of the Aspis Consortium and rebels against House Thrune's rule over Cheliax in pursuit of a nightblade, resulted in a catastrophic failure.34


The Pathfinder Tales novel Nightblade is about the 4714 AR expedition to Fiendslair and is set in part inside of the facility.

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  1. Liane Merciel. Nightblade, 30. Paizo Inc., 2014
  2. Liane Merciel. Nightblade, 8. Paizo Inc., 2014
  3. Liane Merciel, et al. “Living in Shadow” in Nidal, Land of Shadows, 11. Paizo Inc., 2018
  4. This refers to the events of the novel Nightblade.