Draconic Breath Extension

Ability Score Increase: Your Constitution score increases by 1, to a maximum of 20.

Breath Weapon Concentration: You can now choose to concentrate on a breath weapon you can use instead of attacking immediately. When you begin concentration, the breath weapon’s damage increases by 1d10, and increases by another 1d10 for each turn your concentration lasts (up to four turns). This bonus is removed once you attack with the breath weapon or you stop concentrating.

Breath Weapon Misfiring: If your concentration is removed unwillingly, the breath weapon misfires. You take damage equal to the amount of bonus d10 you accumulated, and the breath weapon’s range is one third of its usual (i.e. a 5x30-foot line would be changed to a 5x10-foot line)
Your self-damage is of the same type that the breath weapon deals, but bypasses the natural resistance from your Draconic Ancestry.