Your lineage stems from a dragon progenitor. Choose the kind of dragon from the Draconic Ancestors table. Your choice affects your Breath Weapon and Damage Resistance traits as well as your appearance.

When you take the Attack action on your turn, you can replace one of your attacks with an exhalation of magical energy in either a 15-foot Cone or a 30-foot Line that is 5 feet wide (choose the shape each time). Each creature in that area must make a Dexterity saving throw (DC 8 plus your Constitution modifier and Proficiency Bonus). On a failed save, a creature takes 1d10 damage of the type determined by your Draconic Ancestry trait. On a successful save, a creature takes half as much damage. This damage increases by 1d10 when you reach character levels 5 (2d10), 11 (3d10), and 17 (4d10).

You can use this Breath Weapon a number of times equal to your Proficiency Bonus, and you regain all expended uses when you finish a Long Rest.

You have Resistance to the damage type determined by your Draconic Ancestry trait.

You have Darkvision with a range of 80 feet.

You can telepathically speak to any creature you can see within 30 feet of you. You don’t need to share a language with the creature, but the creature must be able to understand at least one language.

When you reach character level 7, you gain the ability of flight. As a Bonus Action, you spread your wings, using them to fly up into the air. In combat, you can stay in the air for 2 minutes or until you retract the wings (no action required), or have the Incapacitated condition. While in the air, you have a Fly Speed equal to your Speed.

You can whip your tail around, using it as a weapon. Using your STR/DEX modifier, make an attack roll. On a hit, you deal 1d8 Bludgeoning damage. As a Bonus Action, immediately after an attack, you can attempt to grapple a creature with your tail. Roll a contested DEX check. On a success, you grapple a creature with 7 ft. of you until the end of their next turn.

At character level 18, you gain the ability to transform into a dragon matching your ancestry. As an action, you can cast Polymorph, turning into a dragon. Your size is large. While in this form, you gain 30 hit points, and a +5 damage bonus to your Breath Attack. You also gain Immunity towards your chosen ancestry's damage resistance.

After two rounds or once you dismiss the spell as a bonus action, you revert back to your original form, and cannot use this feature again until the next dawn.