The caster rapidly creates a magical barrier between themselves, or an ally, and a harmful effect, such as a "Fireball" or "Dragons Breath", allowing the target an opportunity to shield themselves behind magical cover.  You may target a creature within range, and when that creature is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, it instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

When you cast this spell at 4th level or higher, you may target 1 additional creature for each level above 3rd.