Blast of Metal

You grab some metal and concentrate it to blast into dangourous pellets that do 3d6 force damage, at any range farther than this will do less damage, every distance increase of 20ft removes 1d6/1d8/1d10/1d12/1d20 damage to the spell.

This spell gets more powerful as you level up, at level 5, it is 3d8 force damage, at level 10, it does 4d10 force damage, at level 15, it does 4d12 force damage, at level 20, it does 5d20 force damage.