Circle of the Winter

You conjure a circle of giant icicle, in a 10 feet radius, 10 feet high cylinder at a point a within range. Each creature of your choice in the area must make a Dexdarity saving throw, and on a failed save takes 3d6 cold damege, and its speed is reduce by 10 feet until the start of your next turn. On a succes the creature take half the damege and its speed isn't reduced.

 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.