Cromwell's Railgun

When you cast the spell as a bonus action, you send 3 small objects to orbit around you that are no smaller than a sling shot round. As a reaction on the turns following you can send one of the objects at blinding speed towards a target within range. Make a ranged spell attack against that target. On a hit, the target takes 1d6 piercing damage and 1d4 force damage plus your spellcasting modifier.

At higher levels; When you cast this spell using a spell slot of 2nd or higher the damage of the spell increases by 1d6 piercing and 1d4 force per level above 1st.