A Confusion Ward is used to confuse demons/corelings into not recognizing someone as human. Combined with a Ward of Unsight, it can make somebody effectively invisible. In combination with other wards, it can make them forget their target.
Confusion wards radiate a field of disorientation that can cause creatures to become dizzy and lose their sense of direction. Unless prey is in sight, affected coreling drones will often forget what they are doing, wandering away harmlessly.