air shield

you yell out "air shield" and a green tinted, semi translucent shield, no wider then 5 feet on any side instantly appears at any point within range. this shield has hp equal to 1d4 + spell attack bonus and disappears once it reaches 0 hp or the concentration is broken. you may have and concentrate on a number of shields equal to your proficiency modifier and you may cast more then one shield at a time.