Hogwarts schooling

You cast this jinx on a group of tiny objects or a group of birds within range. The targets start swarming in the air in a 5-foot-diameter sphere in an unoccupied space of your choice. Any creature that starts its turn within 5 feet of the swarm or enters the swarm’s area for the first time on a turn must make a Dexterity saving throw. The creature takes 4d4 slashing damage on a failed save, or half as much damage on a successful one.