Hemomancy

practiced as a close secret amongst those devoted to the manipulation of life itself. Vampires and those under their thrall have been it's longest practitioners. Blood magic harnesses the source of life and transmutes it into arcane power.  

Blood Savant

As part of your arcane recovery you can gain an additional wizard hit die on top of your normal number of hit dice. In addition, as an action, you can roll a hit die in place of a spell. Whenever you cast a spell using hit dice you must roll a number of hit dice equal to the spell's level and you lose hit points equal to the number rolled on the hit dice. The Hit dice rolled are lost until a long rest as if your normal hit dice.

Blood Sense

When you take this arcane tradition at 2nd level, you gain the ability to sense the presence of blood. In a 30 ft. radius around you, you sense the presence of any living creature that has blood (DM's discretion). In addition, you can use your blood in place of ink for your spell book. Whenever you transcribe a spell in your spell book, you roll a number of hit dice equal to the spells level and lose hit points equal to that amount.

Blood Siphon

At 6th level. You've learned how to manipulate both your blood and the blood of those around you. You add the vampiric touch spell to your spellbook if it's not there already. In addition, when you cast vampiric touch you regain the full hit points dealt by the spell instead of half, and the spell has a range of 30 feet. You can cast vampiric touch in this way an equal number of times to your intelligence modifier.

Sanguine Spring

At 10th level, when you drop to 0 hit points but are not killed outright, you can transmute your form into a pool of blood. As a reaction, you transform into a 10 ft. radius pool of blood for 1 minute, in this form you have resistance to all damage and have hit points equal to five times your wizard level. The only action you can take in this form is to revert to your normal form. Once you transform back to your normal form you have 1 hit point. You can't use this feature again until your next long rest.

Sanguine Magus

At 14th level, you learn to master the essence of blood magic. Whenever you deal necrotic damage to a creature with a spell  of 1st level or higher, you gain half the damage dealt as hit points. In addition, you can expend a number of wizard hit dice equal to your intelligence modifier and add the numbers rolled to any spell of 1st level or higher that deals necrotic damage. In addition, when you lose hit points from expending your hit dice, you only take half the normal damage.