Blinding Bolt

The target hit by the bolt takes an extra 3d6 Radiant damage from the attack, and the target has the Blinded condition until the spell ends. At the end of each of its turns, the Blinded target makes a Constitution saving throw, ending the spell on itself on a success.

Using a Higher-Level Spell Slot. The extra damage increases by 1d6 for each spell slot level above 3.