Burning Simoom

Casting value of {6}. If successfully cast, pick 1
enemy unit within 12" of the caster that is visible
to them and roll a number of dice equel to the
number of models in that unit. For each 6, that
unit suffers 1 mortal wound. If the casting roll
was 10 or more, that unit suffers 1 mortal wound
for each 5+ instead of 6.