This guy spawns in the well room area, far to the left side of the zone. His spawn is the last one before the drop off from the one room to the other. That will make sense when/if you explore the room. Approximate loc is n1700, 1500.
Taskmaster Yajo drops a "Pouch of Supplies" that is one of three items needed to release the prisoners from Nurga to become quest mobs in their "home town". See my post under Overseer Pruckib for some more info on this.