Crystal Dragon's Breath

You breathe a cloud of sparkling mist into a 30ft line, 5ft wide. Each creature in line must make a constitution saving throw or take 3d8 Force damage as crystals burst across their bodies, dealing an additional 1d8 force to all creatures within 5ft of them. 

When you cast this spell using a spell slot of 3rd level or higher the damage (of the 3d8) increases By 1d8 for each slot level above 2nd