Unseen Barrier

This spell creates a stationary wall of solid, glass-like air that remains in the position it was cast in. The barrier is 10 feet in length and width and roughly 3 inches thick but can be formed to fit other spaces, as long as it doesn't exceed its maximum dimensions. The barrier cannot be seen by anyone other than the caster unless detected through magical means. While standing behind this barrier you are granted three-quarters cover. The barrier can be summoned on solid ground or mid-air, in both cases it will remain where it is without moving for the duration of the spell. The wall itself has half of your hit point maximum and vulnerability to thunder damage.