Chilling Strike

Your weapon becomes cloaked in a freezing mist that chills whoever it strikes to the core. 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 attack deals an extra 1d6 cold damage and the target has disadvantage on weapon attacks, a creature affected by this spell can use a bonus action on each of its turns to attempt a Constitution saving throw ending the effect on a success.

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