Open your Quests list and select The Bozak Horde:
The tracker will then lead you to the Tower or Embers' hideout, depending on whether you are currently in the Slums or the Old Town.
Once inside the save zone, find a poster with Bozak, the psychopath, and enter the new area by selecting the poster.
The Slums Tower -> the poster can be found near the Tower's shop.
Troy's Tower in Old Town -> it is placed in a room with the shopkeeper, below Troy's Loft.