Blood of the Ancient

You tap into your draconic bloodline, creating an explosion of energy before ascending into latent dragon form. All creatures in an area 60 feet around you must make a Dexterity saving throw, or take 10d6 damage of your bloodline's type. 

You then transform into an ancient dragon of your bloodline. Your game statistics are replaced by the statistics of an ancient red or gold dragon, other than the breath weapon, which changes to an element that matches your ancestry. You retain your alignment and Intelligence, Wisdom, and Charisma scores if they are higher. You also retain all of your skill and saving throw proficiencies, in addition to gaining those of the dragon. If the dragon has the same proficiency as you, and the bonus listed in its statistics is higher than yours, use the creature's bonus in place of yours. You can't use any legendary actions or lair actions of the new form.

You assume the hit points and hit dice of the new form. When you revert to your normal form, you return to the number of hit points you had before you transformed. If you revert as a result of dropping to 0 hit points, any excess damage carries over to your normal form. As long as the excess damage doesn't reduce your normal form to 0 hit points, you aren't knocked unconscious.

You retain the benefit of any features from your class, race, or other source. When you transform, your equipment also transform to suit your dragon form. During this spell's duration, you can use your action to re-assume your regular form.