Blood Boil

Blood Boil has a casting value of 6.
If successfully cast, pick an enemy unit within 18" of the caster that is visible to them. That unit suffers a mortal wound.
If a model was allocated any wounds caused by this spell but was not slain, roll another dice. On a 4+ that model suffers another mortal wound. If the model is still not slain, roll another dice. It will suffer another mortal wound on a 4+. Keep rolling dice in this way until either the model is slain or you fail to cause a mortal wound.