Blood Magic

Blood Magic is often considered by many to be an unholy or even outright evil kind of magic, responsible for enabling the horrific actions of many across the multiverse. Despite this, there are some out there who believe it is only as dangerous as the one who wields it, and that a careful hand can master it without issue. You might have learned this magic from a mentor in secret, or perhaps it is widely accepted where you studied. Some trade favors to devils to learn the dark and ancient arts of blood magic.

Rules Tip: Bloodied is an important mechanic for this subclass. Bloodied refers to when any character or monster is below half their maximum hit points.

Forbidden Magic

Beginning when you select this school at 2nd level, you learn some of the secrets of blood magic. You may choose to use a dagger or similar implement as your spellcasting focus. When you do, roll one of your hit dice, and you reduce your current hit points by that amount. Add that much damage to one damage roll the spell requires, or increase the spell save DC required by the spell by half the die roll rounded down.

(A creature is considered Bloodied when they are below half their starting hit points. A creature is in Critical Condition when they are below one quarter of their starting hit points.)

Siphon Lifeforce

Starting at 2nd level, you may use your action to force a creature within 30 feet of you, that has blood and is bloodied, to make a wisdom saving throw against your spell save DC. On a failure they take 3d4 necrotic damage. At 6th level this becomes 3d6, at 10th it becomes 3d8 and at 14th level this becomes 3d10.

In addition, when you deal damage to any creature with this effect, you can use your reaction to gain up to twice your constitution modifier in temporary hit points. You may gain these temporary hit points a number of times equal to your proficiency bonus. You regain all uses of this ability on your next short rest.

(A creature is considered Bloodied when they are below half their starting hit points.)

Dark Augmentation

So long as you have used a Blood Magic class feature within the last turn, you have a +2 to your AC.

Blood Offering

Beginning at 10th level, you learn how to manipulate the power of blood to make your spells more potent.

When you cast a spell that uses a spell slot, you may expend and roll of number of your hit dice equal to the level of the spell and reduce your current hit points by that amount. You may reroll any number of damage dice for this spell once, or force a target to reroll any number of dice rolls caused by the spell once.

Vitality Drain

Starting at 14th level, you gain the ability to use an unwilling participants vitality to fuel your dark magics. If you are within 5 feet of another being who is Bloodied, you may attempt to siphon their life force to fuel your class abilities. They make a constitution saving throw against your spell save DC. If they fail, for the rest of your turn you may activate your Forbidden Magic or Blood Offering features using a D8 and removing the total from the unwilling participant.

If the target is in Critical Condition, they have disadvantage on their saving throw, and you roll a D12 for Forbidden Magic or Blood Offering.

(A creature is considered Bloodied when they are below half their starting hit points. A creature is in Critical Condition when they are below one quarter of their starting hit points.)