Path of the Blood Mage

In a world filled with powerful casters and magical monstrosities, even the wildest of cultures study and practice the arcane arts. Barbarians are no exception, and those who embrace these mystical powers follow what is known as the Path of the Blood Mage. Rather than drawing their powers from their intellect, an esoteric oath, or some higher power, Blood Mages gain magical might from pain, sacrifice, and the essence of life that flows through their veins. Blood Mages understand that their is an innate power in living beings--much like the Ki used by monks--and that the greatest of these powers come from within oneself. As a Blood Mage takes damage, their abilities grow, so that when they teeter on the brink of death, they are transformed into truly formidable arcane warriors.

If you choose to play this subclass, ask yourself: why have you chosen such a grisly course in your life as a barbarian? Were you raised in a tribe or village that regularly trains its young in the ways of blood magic, or did you discover your powers independently? Did some terrible tragedy drive you into a frenzied madness that unleased your magic, or did it emerge as a result of some freak accident? Do you use your powers to defend those who cannot defend themselves, or do you use them for vengeance? Do you fear the pain you must withstand in order to access your abilities, or do you revel in it? 

Spellcasting

Cantrips. At 3rd level, you learn two of the following cantrips: produce flame, resistance, shillelagh, blade ward, fire bolt, true strike. You learn another cantrip from this list at 10th level.

Spell Slots. The Blood Mage Spellcasting table is equivalent to that of the Eldritch Knight (see Player's Handbook) and shows how many spell slots you have to cast your spells of 1st level and higher. To cast one of these spells, you must expend a slot of the spell's level or higher. You regain all expended spell slots when you finish a long rest. For example, if you know the 1st-level spell thunderwave and have a 1st-level and a 2nd-level spell slot available, you can cast thunderwave using either slot.

Spells Known of 1st-Level and Higher. At 3rd level, you know three 1st-Level spells chosen from the following list: jump, longstrider, thunderwave, heroism, thunderous smite, wrathful smite, hunter's mark, expeditious retreat, false life, mage armor, shield. The Spells Known column of the Blood Mage Spellcasting table shows when you learn more spells of 1st-level or higher. Each of these spells must be chosen from the following list: 2) barkskin, darkvision, enhance ability, flame blade, protection from poison, magic weapon, blur, cloud of daggers, enlarge/reduce, scorching ray, spider climb; 3) call lightning, feign death, meld into stone, protection from energy, water walk, aura of vitality, blinding smite, crusader's mantle, elemental weapon, fireball, lightning bolt; 4) stone shape, stoneskin, wall of fire, aura of life, death ward, staggering smite, polymorph. When you gain a level in this subclass, you can replace one of the spells you know with another spell of your choice from the aforementioned list. The new spell must be of a level for which you have spell slots.

Spellcasting Ability. Constitution is your spellcasting ability, since you draw your powers from your own lifeblood. You use your Constitution whenever a spell refers to your spellcasting ability. In addition, you use your Constitution modifier when setting the saving throw DC for a spell you cast and when making an attack roll with one. Spell save DC = 8 + your proficiency bonus + your Constitution modifier. Spell attack modifier = your proficiency bonus + your Constitution modifier.

Arcane Fury

Starting at 3rd level, when you cast a spell, you can infuse that spell with your barbarous rage. If you cast a spell that deals damage (such as thunderwave or wall of fire), you add damage to that spell equal to your rage damage, as seen on the Barbarian class table.

Sanguine Vengeance

At 6th level, your ability to channel your blood magic rises to new, grisly heights. When you take damage, you can add half that damage (rounded down) to your next attack, regardless of whether that attack is physical or magical in nature. You must finish a short rest before you can use this feature again.

Mage's Madness

Beginning at 10th level, you gain the ability to wield both physical weaponry and spells simultaneously, to devastating effect. When you enter a rage, you can choose to enter a "maddened" rage. For the duration, you can use your bonus action to cast spells from your available spell list. In addition, you can perform the somatic components of these spells even when you have weapons or a shield in one or both hands. When your rage ends, you gain a level of exhaustion.

Grisly Overchannel

Beginning at 14th level, your mastery of blood magic reaches lengths unparalleled by even the deadliest warriors and spellcasters. However, this power comes with a terrible cost. When you land a blow with one of your barbarian weapons, or when you cast a spell that deals damage, you deal the maximum damage possible with either that weapon or spell. You take 2d12 necrotic damage the first time you do this. Each time you do it thereafter before finishing a long rest, the damage increases by 2d12. This damage ignores resistance and immunity.