Booming Blade (TCoE Drei's Version)

You execute a melee strike using your weapon (the material component used in this spell) against a creature within 5 feet. On a successful hit, the target suffers the weapon's standard damage and is instantly enveloped in a crackling field of thundrous energy. If the target willingly moves 5 feet or more before the start of your next turn, the energy detonates, dealing 1d8 thunder damage and ending the spell.

At Higher Levels. At 5th level, the melee attack deals an extra 1d8 thunder damage to the target on a hit, and the damage the target takes for moving increases to 2d8. Both damage rolls increase by 1d8 at 11th level (2d8 and 3d8) and again at 17th level (3d8 and 4d8).