Cassie's Ice Knife

You create a shard of ice and fling it at one creature within range. Make a ranged spell attack against the target. On a hit, the target takes 1d10 piercing damage. Hit or miss, the shard then explodes, covering the ground in a 10ft radius of permafrost. This frosty sphere causes every target caught in it to make a DC 14 DEX save, or they fall prone and 2d6 cold damage.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the cold damage increases by 1d6 for each slot level above 2nd, and the DEX save increases by 1 per level.