Kreistov Vanderson is the Ar-Ulric (chief priest of the cult of Ulric). He first encountered the Warriors after their initial quest, Death Below Karak Azgal, when the emerged from the local tavern, The Fusty Duck.
Incredulous of their tale, the Ar-Ulric sentenced the Warriors to death, suspecting them of being spies for the forces of Chaos. It was only when word was received from Grimcrag Grunnson himself that the Ar-Ulric was convinced to release the Warriors.
Having heard of their exploits in defeating the Orc Warlord Gorgut, the Ar-Ulric hired the Warriors to defeat the Skaven infesting the sewers below Middenheim.