Warding barrier

You create two 5ft wide, 10ft tall and 1 inch thick magical barriers somewhere on a platform within range. It is opaque, smooth and light grey. A medium or smaller creature can use it as full-cover. A Larger or larger creature may need multiple walls next to each other to get more than either 3/4 cover or half cover respectively.

The walls each have an AC of 10 and 40 hp each, this health can not be restored. When the health of a wall is reduced to less than one, it shatters and disappears. 

When the spells ends or the caster loses concentration the walls shatter and disappear.