race features:
Size. Your size is that of your body before you transcended life. Your size is either Small or Medium.
Blood Magic. Born of darkness, you can call on your curse to produce magical effects. You can cast charm person with this trait. Starting at 3rd level, you can cast spider climb with it, and starting at 5th level, you can also cast gaseous form with it. Once you cast a spell with this trait, you can’t cast that spell with it again until you finish a long rest. Charisma is your spellcasting ability for these spells.
Bloodthirst. You can drain blood and life energy from a willing creature, or one that is grappled by you, incapacitated, or restrained. Make a melee attack against the target, using either Strength or Dexterity for your attack roll. This attack hits automatically if the creature is willing. If you hit, you deal 1 piercing damage and 1d6 necrotic damage. The target’s hit point maximum is reduced by an amount equal to the necrotic damage taken, and you regain hit points equal to that amount. The reduction lasts until the target finishes along rest. The target dies if this effect reduces its hit point maximum to 0.
If you go for 7 days without dealing this damage, your hit point maximum is reduced by 1d6 per week. This reduction lasts until you deal damage with your Bloodthirst ability and complete a long rest.
Change Shape. You can use your action to magically assume the shape of a bat as if affected by the polymorph spell, but you retain your Intelligence, Wisdom, and Charisma scores. You also retain all of your skill and saving throw proficiencies.
You can stay transformed for a number of minutes equal to your proficiency bonus. You then revert to your normal form. You can revert to your normal form earlier by using a bonus action on your turn.
After you use this trait, you cannot do so again until you finish a long rest.
Darkvision. Accustomed to dark dwellings and the night sky, you have superior vision in dark and dim conditions. 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 can't discern color in darkness, only shades of gray.
Sunlight Sensitivity. You have disadvantage on attack rolls and Wisdom (Perception) checks that rely on sight when you, the target of the attack, or whatever you are trying to perceive is in direct sunlight.
Undead Body. Your body differs from that of the living in the following ways: You have advantage on saving throws against being poisoned. You have resistance to necrotic and poison damage. You have a vulnerability to radiant damage. You don’t need to eat, drink, or breathe. You are immune to disease.