Blood Domain

Those who take upon the ways of blood magic take upon a dark curse. Most of them sacrifice something or.... someone.... close to them to obtain their powers, but in doing so usually receive a curse from the act, and lose many of their ways of helping others with this magic without risking harm to themselves. 

Those who do take upon this volatile and hostile magic usually take up to hiding outside of major establishments, where they can safely 'procure' the required things for some of their rituals, and fanatical plans.

Anatomy Expertise

 Starting at 1st level, you gain proficiency in medicine.

Blood Magic

Starting at first level, you get a pool of points equal to your Wisdom modifier known as Blood Points (A limit of 5, a minimum of 1.) When you make a melee attack, you may spend a Blood Point to make a second attack as a part of the attack action taken. You regain these points after completing a long rest.

As a downside to taking up this domain, you've made a dark exchange, a curse placed upon you. Should you concentrate on a spell that effects another creature other then yourself in a beneficial manor, your movement speed is halved for the duration and you are vulnerable to all damage whilst concentrating, as your magic is not meant to aid others.

Channel Divinity: Congeal Blood

Starting at 2nd level, you can use your Channel Divinity to congeal your blood momentarily. 
As an action, you bring forth your symbol or holy emblem, and for the next minute your movement speed cannot be reduced by any means.

Transfusion Expert

Beginning at 6th level, your blood magic capabilities expand. As a bonus action after making a melee weapon attack, you regain 1/2 of the weapon damage dealt by the previous attack. 

You can use this feature a number of times equal to your Wisdom modifier (a minimum of once). You regain any expended uses when you finish a long rest.

Vampiric Weapon

Beginning at level 8, you may use an action, you can spend 2 hit dice from this class to form a weapon that you are proficient with in your hands. (Ranged weapons do not require ammo, but firearms cannot be produced with this ability.) This weapon lasts for one minute, and is treated as a magical weapon. As a part of this action, you may make a single attack with the created weapon against a creature within range. Should this attack score a critical hit, you roll your damage dice for the weapon three times instead of twice, and you regain 1 hit dice for this class. (This does not stack with other effects allowing you to roll additional critical damage, such as piercer or barbarians brutal critical.)

Blood Ascension

Starting at 17th level, you reach the pinnacle of the dark magic that is both life and death. You may use one of the following abilities once per long rest.

1. When you cast a necromancy spell that has a casting time of one action, you may spend a blood point to instead cast it as a bonus action.
2. As an action, you ascend to the pinnacle of your blood magic, honing your transference abilities. Reduce your maximum hit points by 30 (Unavoidable by any means.) which are restored only upon benefiting from a long rest. For the next minute, you receive the following benefits.

• 30 temporary hit points upon using this ability.
• Any time you cast a spell that causes a creature to receive healing, you may add your wisdom modifier to the amount healed.
• As a bonus action, you may change the form of your vampiric weapon once into another weapon you are proficient with (bar firearms).

After using either of these abilities, NEITHER of them can be used again until you benefit from a long rest.