race features:
Skeletal Tail: Your tail is now skeletal, with protruded spines and tightly stretched skin and is a natural weapon, which you can use to make unarmed strikes. If you hit with them, you deal piercing damage equal to 1d6 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike.
Unholy Venom: When you make a successful attack against a creature with your Skeletal Tail, you can use a bonus action to inject them with your venomous prongs. The creature must succeed on a Constitution saving throw or becomes poisoned until the end of your next turn. The save DC for this saving throw equals 8 + your proficiency bonus + your Constitution modifier. Once you use this trait you cannot use it again until you complete a short or long rest.