+2 Dexterity +1 Charisma

You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You cant discern color in darkness, only shades of grey.

Demonic Adaptability grants you a choice of two options. A camouflage ability or fire resistance.

You know the minor illusion cantrip. Once you reach 3rd level, you can cast the witch bolt spell once per day. When you reach 5th level, you can cast the hold person spell once per day. Charisma is your spellcasting ability for these spells.

You have a pair of large bat-like wings from your shoulder blades while in your true form, reflecting your hellish nature. The following effects can only be had in your true form while wearing only light armour.
Gliding: You can use your wings to glide, negating damage from a fall of any height and allowing 15 feet of forward movement for every 5 feet descended at a speed of 30 feet per round. You are also able to use your wings to give a boost to your jumps. As an action, you can double your jump distance.
At 6th level your wings grow steadier and they can carry you for a short time per day. You may gain a fly speed of 30ft for 1 minute per constitution modifier per day.
At 12th level your wings are stronger and able to carry you for long periods of time, granting you a permanent fly speed of 30ft.