Silver Dragonborn Breath Weapon

You can instead of your normal breath weapon, you exhale paralyzing gas in a 15-foot cone. Each creature in that area must succeed on a Constitution saving throw. On a failed save, the creature becomes paralyzed for equal to your constitution modifier in rounds (min of 1). A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. The DC for this saving throw equals 8 + your Constitution modifier + your proficiency bonus.