Chilling Smite

The next time you hit a creature with a weapon attack before this spell ends, the weapon freezes over with jagged blue ice, and cold air swirls around the weapon. The attack deals an extra 2d12 cold damage to the target. The target must then make a Constitution Saving throw against your spell DC. If the target fails the target becomes paralyzed, for one turn. The paralysed target becomes encased in ice. If the target succeeds in the saving throw, they just take the cold damage. 

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the extra damage increases by 1d12 for each slot level above 3rd.