In Midnight Tides
Stonecutters at a quarry in Letheras accidentally breached the forgotten prison of a Khalibaral demon. The hungry, insane, and cowardly creature immediately began killing workers as well as the necromancer hired to eliminate it. Its murderous spree was halted only by the appearance of the Jaghut Huntress who had originally imprisoned it long ago. She sealed the mouth of the cave with ice before pondering the question of what to do with it. Bugg who had been observing her, made a suggestion.
It was not explicitly revealed, but Bugg later remarked that the tunnels beneath the newly shored up Fifth Wing of the Eternal Domicile were now chilly for reasons he thought best not to explain to his master, Tehol Beddict.