Booming Blade

You strike a creature with a weapon, empowered with thunderous energy, trapping the target in a bubble of thunderous energy, bursting if they breach its barrier. Most people consider this to be the superior melee cantrip. I would disagree as in most cases a creature will have a ranged option to use on their turn and forced movement will not cause the extra damage to activate.

Effect

As part of the action to use this spell, you must make a melee attack with a weapon against one creature within the spell's range, otherwise the spell fails. On a hit, the target suffers the attack's normal effects, and it becomes sheathed in booming energy until the start of your next turn. If the target willingly moves before then, it immediately takes 1d8 thunder damage, and the spell ends.  At higher Levels. At 5th level, the melee attack deals an extra 1d8 thunder damage to the target and the damage the target takes increases to 2d8. Both damage rolls increase by 1d8 at 11th level and 17th level.

Side/Secondary Effects

The sense of disappointment you feel that forced movement will NOT trigger the spell's extra damage.

Manifestation

This spell is characterized by a humming aura of thunderous energy contained in an easily disturbed field around your target, blasting inward if your target moves from their current position before the spell ends.

Source

The magic needed for this spell is pulled from The Weave. Artificers might have some kind of vibrational field generator or movement sensitive sonic detonator attached to their target after a strike with a weapon.

Material Components

A weapon. Duh.

Gestures & Ritual

You need to swing the weapon first.

Related School

Evocation

Related Element

Air

Effect Duration

1 round

Effect Casting Time

1 action

Range

5 feet

Level

0

Applied Restriction

The fact that multi-attack is usually better.