Chill Smite

The next time you hit a creature with a weapon attack before this spell ends, the weapon gleams white and becomes coated with ice crystals the moment before you strike.  The hit then deals an extra 2d6 cold damage to the target.  A creature that is hit must make a Constitution saving throw.  On a failed save, the creature's wound is covered with frost that deals an additional 1d6 cold damage at the start of the next turn and each following round for the duration of the spell.  On a successful save, the spell ends.

At higher levels- When you cast this spell using a spell slot of 3rd level or higher, the extra initial damage increases by 1d6 for each slot level above 2nd.