Booming Blade

You brandish the weapon used in the spell's casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack's normal effects and then becomes sheathed in booming energy until the start of your next turn. If the target willingly moves 5 feet or more before then, the target takes 1d8 thunder damage, and the spell ends.

Cantrip Upgrade. This spell's damage on moving increases by 1d8 when you reach 5th level (2d8), 11th level (3d8) and 17th level (4d8). This spell's damage on hit increases by 1d8 when you reach 11th level (2d8) and 17th level (3d8).