Discus of Light

You fire a ring of light forwards in a line 30 feet long and 5 feet wide. Each creature in the line must make a Dexterity saving throw. A creature takes 2d8 radiant damage on a failed save, or half as much on a successful one.
At the start of your next turn, the disc returns to you, causing each creature in the line to make the same saving throw.
At Higher Levels.
When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d8 for each slot level above 1st.