Wall of Frost (improved)

You create a wall of frost you can shape a flat surface made up of ten 10-foot-square panels. Each panel must be contiguous with another panel. In any form, the wall is 1 foot thick and lasts for the duration. you can use your bonus action to move it 20 feet  

If the wall cuts through a creature's space it must make a Constitution saving throw. On a failed save, the creature takes 6d6 cold damage and is frozen, or half as much damage on a successful save.

if a creature casts a fire spell, deals, or takes fire damage  it is immune for 1 round

At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the damage the wall deals when it appears increases by 2d6 for each slot level above 6th.