Models with the Mark of Tzeentch only. The bearer can make a single re-roll of one or more dice rolled to cast or dispel a spell. The second result(s) stand. This can negate the effects of a Miscast and cause an Irresistible Force (and the equivalent results when dispelling). If the bearer casts a spell with Irresistible Force using the staff's re-roll ability, the staff will exhaust its power and cease working for the rest of the battle.