This special rule can only be used by a Cult Magister that has joined a unit. Before making a Casting roll, this model may make a sacrifice. One model belonging to this model's unit is immediately removed from play as a casualty. This model may then modify their Casting roll by adding the Wounds characteristic of the sacrificed model to the result.

Note that this is a modification to the result of a roll - it does not negate a roll of a natural double 1.