Blizzaga

A tiny radiant snowflake drifts upward from your arcane focus to a point you choose within range, upon arriving grows thousands of times its original size before exploding into a cloud of icy dust. Each creature in a 25-foot-radius sphere centered on that point must make a Constitution saving throw. On a failed save, a creature takes 14d12 cold damage and is slowed for 1 minute. On a successful save, it takes half as much damage and isn't slowed by this spell.