Cold's Kiss

A silvery-blue streak flashes from your crystal to a point you choose within range and then opens a rift to the Elemantal Plane of Cold. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 8d6 cold damage on a failed save, or half as much damage on a successful one.

The cold seeps around corners. It freezes wet surfaces in the area for 1 round, acting as difficult terrain.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.

a tiny clear crystal of no less than 50gp value, not used up in the casting