You shoot out a straight, 5ft.³ wide, radiant beam of light --starting at you-- that will go indefinitely until blocked or obscured (out of your sight) and lasts until it's your turn again. Any creatures inside of that beam makes a DC 14 Dex saving throw. On a failed save, they take 4d8 radiant damage, and half as much on a successful one. If a creature passes through the beam, they take 4d8 radiant damage automatically.
This spell's damage increases by 2d8 once on 7th level (6d8), 11th level (8d8), and 15th level (10d8). Additionally, for every spell slot that you spend above 2nd level, you gain an additional 2d8 damage and increase the beam's range by 5ft.³ ( eg. using a 3rd level spell slot would get you a 10ft.³ wide beam of light instead of a 5ft.³ wide one)