Disarm all six wand traps on Level 2 of Irenicus' Prison dungeon, during Chapter 1. These must be disarmed before leaving the dungeon, and can only be deactivated by finding each trap's corresponding wand key. There are six keys to find:
Dropped by the Otyugh on Level 1.
In a bedroom on Level 1, beyond the location of the Otyugh.
In the room where Khalid's corpse is found on Level 2; there are three keys in here.
Dropped by the Clone of Ellesime on Level 2, in the room near to where Khalid's corpse resides in.