Chilling Smite

The next time you hit a creature with a melee weapon attack during the spell’s duration, your weapon sparks with misty shimmer and the attack deals an extra 1d6 cold damage to the target and causes the target to shiver. At the start of each of its turns until the spell ends, the target must make a Constitution saving throw. On a failed save, it's movement speed is halved. On a successful save, the spell ends. 

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the initial extra damage dealt by the attack increases by 1d6 for each slot.