Crushing Smite

The next time you hit a creature with a weapon attack before this spell ends, the weapon coats itself with seafoam as you strike. The attack deals an extra 2d6 magical bludgeoning damage to the target, which becomes battered by waves lapping against it's feet. The targets speed is halved and if the creature is of size medium or smaller it is considered grappled. To escape it must make a Strength or Dexterity check equal to your spell save DC. 

At Higher Levels. When you cast this spell using a spell slot of 2rd level or higher, the extra damage increases by 1d6 for each slot level above 1st