The fourth of Werdna's towers, disguised to the outside world as the "Guild for the Surprise Taxation of the Unaware."
When the party visited the Tower of Ardara, they discovered that it had long ago been ransacked of anything of value; whereas the other towers were disguised as places no reasonable person would visit, the unusual disguise for this tower apparently attracted an unsavory criminal element. These criminals established a thieves guild in the tower, claiming it as their own, themselves becoming The Guild for the Surprise Taxation of the Unaware.