Arctic Aura

You conjure a protective field of bitter frost around you in a 15-foot Emanation for the duration. 

The spell affects enemies and allies within the field. Any creature within the Aura has their Speed halved within the Emanation, and whenever the Emanation enters a creature’s space and whenever a creature enters the Emanation the creature must make a Constitution saving throw. On a failed save, the creature takes 3d6 Cold damage. On a successful save, the creature takes half as much damage. A creature makes this save only once per turn. 

If a creature ends its turn inside the Emanation they are hindered by ice for 1 round, or until they or another creature within reach uses an action to break away the ice. A creature hindered by ice has it's speed reduced to 0.

Using a Higher-Level Spell Slot. The damage increases by 1d6 for each spell slot level above 4th.