Brass Dragonborn Breath Weapon

You can instead of your normal breath weapon exhales repulsion energy in a 15-foot cone. Each creature in that area must succeed on a Constitution saving throw. On a failed save, the creature falls unconscious for equal to your constitution modifier in minutes (min of 1). This effect ends for a creature if the creature takes damage or someone uses an action to wake it. The DC for this saving throw equals 8 + your Constitution modifier + your proficiency bonus.