Blood Magic

Blood magic is a wizard specialty that uses hemocraft for arcane purposes. The blood magic school was created by Matthew Mercer.

Description
Blood magic relies on using the caster's own life energy to channel and enhance their arcane abilities. As with most hemocraft, blood magic was once a secret of the Claret Orders that has since spread; also as with most hemocraft, it is misunderstood and feared in many places, including Tal'Dorei.

Powers and abilities
This section is based on pp. 178-179 of the Tal'Dorei Campaign Setting Reborn.

Blood Channeling
Beginning at 2nd level, a blood magic wizard whose hit points are below their maximum can use their own body as their arcane focus. They may also use their own vitality to replace expensive components, taking 1d10 necrotic damage per 50 gp of the component cost (with a minimum damage of 1d10 even component costs below 50 gp). This damage cannot be reduced, and if the damage takes the wizard to 0 HP, the spell will fail and not be expended.

Sanguine Burst
Also beginning at 2nd level, a blood magic wizard may, when rolling damage for a leveled spell they've cast, take necrotic damage equal to the spell level to reroll up to their Intelligence modifier damage dice. The necrotic damage cannot be reduced, and they must use the new rolls.

Bond of Mutual Suffering
Beginning at 6th level, when a creature the blood magic wizard can see hits with an attack, the wizard may use their reaction to bind themselves to the attacker. The attacker then takes damage equal to the damage of the attack. This may be done once per rest, and does not work against constructs or undead. At level 14, this ability may be used twice per rest.

Glyph of Hemorrhaging
At level 10, when a blood magic wizard deals damage to a creature with a spell, they may also choose to curse that creature for the next minute. A creature cursed by this feature takes an extra 1d6 necrotic damage whenever they are hit by an attack. The creature may, at the end of each of their turns, attempt a Constitution save against the wizard's spell DC to end the curse. This ability cannot be used against constructs or undead, and may be used once per rest.

Thicker than Water
At level 14, when a blood magic wizard regains hit points via a spell or magical effect, they also regain an additional number of hit points equal to their proficiency bonus. They also, while concentrating on a spell, are resistant to nonmagical bludgeoning, piercing, and slashing damage from attacks.

Notable Blood Magic wizards
Honor Kinnabari - a tiefling woman from Westruun and a spellwright in the League of Miracles