Thunder Thrust

As part of the action used to cast 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 a shimmering aura surrounds them making them feel sluggish, halving their movement rate until the beginning of your next turn.

This spell's damage increases when you reach higher levels. 

At higher level

The melee attack deals an extra 1d8 thunder damage to the target at 5th level (1d8) 11th level (2d8) and 17th level (3d8).