Treason of Tzeentch

has a casting value of 5. If successfully cast, pick 1 enemy within 18" of the caster and visible to them. Roll a number of dice equal
to the number of models in that unit. For
each 6, that unit suffers 1 mortal wound. If
any models are slain by this spell, subtract
1 from hit rolls for attacks made by that
unit until your next hero phase.