Your features are enhanced by the demonic blood that seeps through you

You are immortal

Thanks to your body being made for living in darkness, you can see in it. You can see in darkness as if it were bright light up to 30 feet and an additional 30 feet as if it were dim light

You sear and burn in the light of the sun, your flesh immolating. If you end your turn in direct sunlight you take 20 damage. You also have disadvantage on any attack rolls and ability checks when in direct sunlight

Due to inherent darkness in your soul, you have resistance to necrotic damage, You’re also vulnerable to radiant

Your teeth might as well have been that of a child’s before. The damage for your bite and claws increases to 1d6. At fifth level it increased to (2d6), 11th (3d6), and 17th (4d6).

You can speak read and write common abyssal and one other language of your choice

Each ration of blood heals you for 1d4+1 hit points while a pint heals you for 2d4+2 hit points. You need a pint of blood a week to survive. You may use this a number of times equal to your proficiency bonus

Your eyes almost sparkle as you look towards people drawing them in to believe what you say. Your proficient in persuasion and deception

Your soul is entwined with fire in aggressive and charming ways. You gain the ability to case charm person as a first level spell a number of times equal to the amount of tails you have. You also gain the ability to cast the fire bolt cantrip. At 4 tails you gain the ability to cast charm person as a 2nd level spell and at 7 you can cast it at third