Arctic Air

You unleash a freezing aura. Creatures that start their turn within a 20ft sphere of you must succeed a Constitution save, or take 2d8 cold damage and have their speed reduced by half until the start of their next turn. Creatures that succeed their saving throw take half as much damage and their speed isn't reduced.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d8 for each slot level above 3rd.