Conjure Lead

Tiny metal cylinders explode from your focus, or a direction you point, in a burst of fire. In a 5ft by 120ft line from you, all creatures must make a dexterity saving throw. Each consecutive creature hit after the first (in line from how far they are from the caster, closest to farthest) gets a stacking +1 to their dexterity save. 

Targets who fail the save take 12d12 piercing dammage, those who succeed take half