The study of blood magic is a contentious one. Originally created as a method of allowing wizards to cast spells in areas where magical forces were weak or even unavailable, the study of blood magic adapted to allow blood mages, as they are now called, to use their blood as a power source to fuel their spells and circumvent the need for magic energy entirely. So long as their life force holds out, a blood mage can cast spells indefinitely. But the study and use of blood magic carries a significant risk to the wizard as they must calculate how much of their blood, and thus their own life, they can safely use to fuel the spell they are attempting to cast. Because of the danger to the caster, blood magic is often banned at wizardly schools as there have been too many accidents involving mages who died in its practice to justify its teaching. As a result, the study has fallen out of favor and is even reviled as an abomination for usurping the natural order of the world. 

Drawn to the rumors of unlimited magic power, many evil wizards are eventually drawn to this style of magic and it has become entwined with some of the most vile creatures in history. Tales of these creatures tell of various supernatural abilities, such as controlling other beings' actions by manipulating the flow of their blood or simply causing crippling pain by stopping the flow of blood in another creature with no more than a thought. Rumor or not, blood mages are widely feared and these tales are often held up as proof of the inherent evil associated with the practice of blood magic. 

However, there are cultures and peoples that have learned to harness this style of magic to bolster their own physical ability, deadening their response to pain and even unlocking latent power hidden in their bloodline from distant ancestors who may have been elves, dragons, and other creatures. These practitioners often train in secret schools or monasteries to avoid the association with the more evil forms of the magic or are part of tribes or cultures far from the eyes of greater society. It's said that there are some who even sacrifice their own life force to heal others. These groups and societies often have strict traditions in place to protect their study and remain hidden from prying eyes. 

Defined mostly by rumor, suspicion, and fearful interest, blood magic is typically practiced in secret by creatures of evil and neutral alignment. They may trend towards chaos in some cases, using their power for random acts of violence, or lawful in others, abiding strict traditions to protect their study. Regardless, the rumors about the power of blood magic are well deserved. Blood mages typically practice in secret and those that exist in greater society try to blend in with other lay folk. Their skills in manipulating blood generally afford them great medical ability and some of the more kind practitioners may become travelling doctors, hiding their true magical abilities. 

Blood Magic

At 2nd level, you have learned to fuel your spellcasting with your blood, drawing on your own life force to produce magical effects. When you cast a spell, you may choose to do so without expending a spell slot. If you do, you take 1d6 necrotic damage equal to the level of the spell you cast. This damage cannot be mitigated by resistance or immunity. 

Pain Suppression

Starting at 2nd level, your study of blood magic has hardened your body against pain. While you aren't wearing armor, your AC is equal to 10 + your dexterity modifier + your constitution modifier. 

Blood Sacrifice

Starting at 6th level, you learn to fuel augment your casting by using your blood as a conduit for the magic. When you cast a spell, you may spend a number of hit die equal to your proficiency score. You take the amount rolled as necrotic damage, but add the same amount to the damage or healing from the spell. The type of damage added by this ability may be of any type associated with the spell you are casting. 

 

Latent Bloodline

Beginning at 10th level, your study of blood magic has extended to your own family history and an ancestor who was perhaps a dragon or even a fey creature. Whatever the case, you've learned to tap into that latent power and manifest it as your own.

You discover you descend from one of the following ancestries: Celestial, Demonic, Draconic, Elemental, Fey, or Otherworldly. You gain various bonuses based on the bloodline you select. 

Celestial Bloodline

You've learned to manifest latent celestial power from a distant ancestor in your bloodline. When you select this option, you gain the following benefits:

 

• Increase your strength, constitution, or charisma score by 1, up to a maximum of 20. 
• You gain the Inspiring Leader trait.

 

Demonic Bloodline

You've learned to manifest latent demonic power from a distant ancestor in your bloodline. When you select this option, you gain the following benefits:

• Increase your Strength or Constitution score by 1, to a maximum of 20.
• You have resistance to cold damage and poison damage.
• You have advantage on saving throws against being poisoned. 

 

Draconic Bloodline

You learn to tap into latent draconic power granted by your ancestry. When you select this bloodline, you gain the following benefits:

• Increase your Strength, Constitution, or Charisma score by 1, to a maximum of 20.
• You grow retractable claws from the tips of your fingers. Extending or retracting the claws requires no action. The claws are natural weapons, which you can use to make unarmed strikes. If you hit with them, you deal slashing damage equal to 1d4 + your Strength modifier, instead of the normal bludgeoning damage for an unarmed strike.
• You sprout draconic wings from your back. You gain a fly speed of 30 ft.  

Elemental Bloodline

You've learned to manifest latent elemental power from a distant ancestor in your bloodline. When you select this option, you gain the following benefits:

• Increase your dexterity or intelligence score by 1, up to a maximum of 20.
• Select an elemental ancestry from the following: air, earth, fire, water. You may shapeshift into an elemental associated with that ancestry once per short rest. 

Fey Bloodline

You've learned to manifest latent fey power from a distant ancestor in your bloodline. When you select this option, you gain the following benefits:

• Increase your dexterity, intelligence, wisdom or charisma score by 1, up to a maximum of 20.
• Whenever you have advantage on an attack roll using Dexterity, Intelligence, Wisdom, or Charisma, you can reroll one of the dice once.

Otherworldly Bloodline

You learn to tap into the otherworldly power hidden in your bloodline through a distant ancestor. When you select this option, you gain the following benefits:

• Increase your intelligence or wisdom by 1, up to a maximum of 20. 
• You can speak telepathically to any creature you can see within 60 feet of you. Your telepathic utterances are in a language you know, and the creature understands you only if it knows that language. Your communication doesn't give the creature the ability to respond to you telepathically.

Blood Control

At 14th level, you've learned to manipulate and control the flow of blood within other creatures, causing their body to move against their will or causing crippling pain. You learn the following spells and always have them prepared: Dominate Person, Power Word Stun, Dominate Monster. These spells do not count against your prepared spells and you may cast them using only somatic components. If a creature fails its initial save and is subjected to the effects of these spells and they later succeed on a saving throw, they are stunned until the start of their next turn.