Curse of Years

Pick 1 enemy unit within 18" of the caster that is
visible to them and roll 10 dice. For each 6, that
unit suffers 1 mortal wound and you can roll an
extra dice. For each 5+ on these extra dice, the
target suffers 1 MW and you can roll another dice.
Now, for each 4+, the target suffers 1 MW and
you can roll another dice. Keep rolling dice in this
way, inflicting MWs and reducing the roll needed
to cause them by 1 each time, until either no
wounds are inflicted or the target unit is dest