Your Charisma score increases by 2, and your consitution score increases by 1.

These tieflings mature at the same rate as humans but live a few years longer

Tieflings are about the same size and build as humans. Your size is Medium. 

You can speak, read, and write Common and Deep Speech. 

You have a climbing speed equal to your walking speed.

Thanks to your eldritch heritage, you have superior vision in dark and dim conditions. You can see in dim light within 60ft of you as if you were in bright light, and in darkness as if it were dim light. You cant discern color in darkness, only shades of gray. 

You have resistance to Necrotic damage

You know the spare the dying cantrip. When you reach 3rd level you can cast false life spell as a 2nd level spell once with this trait. When you reach 5th level you can cast the mirror image spell once with this trait. You regain the ability to cast these spells with this trait when you finish a long rest. Consitution is your spellcasting ability for these spells. 

If a blood moon is out while you are asleep, you have a dream (as per the spell, Save DC 16). In this dream, the black goat places a compulsion within your mind, ordering you to carry out some activity as a torrent of images and sensations. When you awaken, you are automaticly affected by a suggestion spell. When you awaken, you are automatically affected by a suggestion spell (save DC 16, cast as a 7th level spell) in addition to the effects of dream, and must carry out the order.