You can use your action to exhale destructive energy. When you use your breath weapon, each creature in a 30-foot line must make a saving throw. The DC for this saving throw equals 8 + your Constitution modifier + your proficiency bonus. A creature takes 2d6 necrotic damage on a failed save, and half as much damage on a successful one. The damage increases to 3d6 at 6th level, 4d6 at 11th level, and 5d6 at 16th level. After you use your breath weapon, you can’t use it again until you complete a short or long rest.

Your Strength score increases by 2, and your Charisma score increases by 1.

Your lack of flesh makes you more difficult to harm with flesh-consuming effects. You have resistance to necrotic and fire damage.

It takes time for dragonborn flesh and scales to completely rot, leaving only skeletal remains. Outside of unusual or magical circumstances, dragonborn skeletons died at least ten years ago. It is unknown how long necromantic energies can sustain their bones, but there exist tales of dragonborn skeletons still walking the earth 300 years after death.

Dragonborn are taller and heavier than humans, standing well over 6 feet tall and averaging almost 250 pounds. Your size is Medium.

Your base walking speed is 30 feet.

As undead creatures, dragonborn skeletons do not need to breath, and thus can exist underwater or in airless environments indefinitely. 

Dragonborn skeletons do need to sleep, in order to restore the necromantic force binding their bones together and sustaining their unlife. However, for dragonborn skeletons, 4 hours of sleep is considered a long rest, rather than 8 hours.

Without flesh to cushion the blows, dragonborn skeletons are vulnerable to bludgeoning damage. They take double damage from bludgeoning effects.

You can speak, read, and write Common and Draconic. Draconic is thought to be one of the oldest languages and is often used in the study of magic. The language sounds harsh to most other creatures and includes numerous hard consonants and sibilants.