Legendary blood line's

• This is a gift you have been born with and is as strong as you are. Not all Dragonborn have what you have and know how to use it in combat.- Bahamut, the Platinum Dragon, King of the Good Dragons, and Angel of the Seven Heavens.
• Through meditation, training, or sheer force of will, you have connected to an ancestral memory of the ancient dragons. A powerful spined tail bursts from the small of your back. Mighty wings burst from your back and you take to the skies to experience a kind of freedom few dragonborn have felt before. As you're still getting used to your wings, you cannot fly indefinitely, only about ten minutes at a time. You can roar like the dragons of old times and cause mass panic.
• When using your breath attack double the amount of damage dice rolled. Your breath attack is now Dexterity saving throw (DC 15 + your proficiency bonus + your Dexterity/Wisdom modifier your choice)
• Increase one ability score by 3, to a maximum of 20.
• Once per short rest you can perform dragons roar, forcing each creature of your choice within 30 feet of you to make a Wisdom saving throw (DC 8 + your proficiency bonus + your Charisma modifier). A target automatically succeeds on the save if it can’t hear or see you. On a failed save, a target becomes frightened of you for 1 minute. If the frightened target takes any damage, it can repeat the saving throw, ending the effect on itself on a success. If an effect would increase the sound of your voice increase the range of this effect accordingly. Example 3 times as load 90 ft.
• You can use your tail as follows:

Tail Attack - As an attack action or part of a multi attack action, you can use your tail to deal 3D6 + STR bludgeoning damage on a successful hit. Opponent must succeed at a DEX Save (DC 10+STR ) or fall prone. If you choose this you cannot use this as a Bonus Action or Reaction until your next turn.*

Going Low (Bonus) & Surprise Trip (Reaction) - If you have not used this as part of your attack action, you can attempt to trip an opponent with your tail. Opponent must succeed at a DEX Save (DC 10+STR) or be knocked prone, stopping all movement for the rest of its turn.*

* Trip does not work on creatures that are immune to the trip action, damage will still apply if used as an attack action.

 FLYING.

You have a flying speed same as your walking speed + 10. You can fly for 10 minutes before your wings get tiered. If you are in the air longer then ten minutes your wings go limp and you crash to the ground taking falling damage. If you take off from the ground you use 15 ft of movement on take off. If you are in the air you can use a glide to take off at no cost to movement.