Black Snow

This Spell is a Rare Spell these type of spell you need to find or unlock from a spell scroll or some other Source(optional rule) 

You create a sphere of black-colored snow that is laced with acid in a 20-foot sphere centered on you. Each creature other than you that is within the sphere must make a Constitution saving throw at the beginning of each of their turns. On a failed save, the target takes 2d6 cold damage and 2d6 acid damage, and has its speed reduced by 10 feet until the end of its next turn. On a successful save, the damage is halved and the target's speed is unaffected.

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