Amaranthine Orb

Amaranthine Orb has a casting value of 7.
If successfully cast, pick a point on the battlefield within 12" of the caster and draw an imaginary straight line 1mm wide between that point and the closest part of the caster.
Roll a dice for each unit (friend or foe, apart from the caster) that has any models beneath this line.
On a 4+ that unit suffers D6 mortal wounds.