Your Strength and Constitution scores increase by 4, your Dexterity and Charisma scores increase by 6.

You can speak,read and write Common, Infernal and Abyssal.

Concubi can fight with their claws, their wings and their fangs. 

As an action, you can change your appearance and your voice. You determine the specifics of the changes, including your coloration, hair length, and sex. You can also adjust your height and weight, but not so much that your size changes. You can make yourself appear as a member of another race, though none of your game statistics change. You can’t duplicate the appearance of a creature you’ve never seen, and you must adopt a form that has the same basic arrangement of limbs that you have. Your clothing and equipment aren’t changed by this trait.

You stay in the new form until you use an action to revert to your true form or until you die.

Your fiendish beguile grants you expertise in the Persuasion and Deception skills. 

At level 1 you can cast Charm Person 

At level 3 you can cast Command 

At level 5 you can cast Sleep 

At level 7 you can cast Suggestion 

At level 9 you can cast Hold Person 

Concubi are able to use their Infernal powers to drain the life and vitality of their victims.

You are resistant to Fire, Psychic, Cold, Poison, Lightning, as well as Bludgeoning, Piercing and Slashing from nonmagical attacks.

You have 75ft of darkvision.

At level 1 you can cast Misty Step and Etherealness

At level 11 you can cast Ray of Sickness

At level 13 you can cast Cone of Cold 

At level 15 you can cast Lightning Bolt 

At level 17 you can cast Fireball 

At level 19 you can cast Gate

You are a Fiend.