Sanguine Soldier

When inhumane methods and diabolical experiments become the norm, innocents suffer. Through such vile subjections, sanguine soldiers were formed. Crafted from the blood of a powerful vampire and subsumed within an unwilling creature, a small handful survived to become monstrous killing machines. Not sharing in the weaknesses of their progenitors except for a bloody thirst, sanguine soldiers are ruthless on the battlefield, tearing their enemies to crimson chunks and replenishing themselves from the death they bring.

Unquenchable Thirst

Beginning at 3rd level, you can drain the blood from your foes to replenish yourself. When you strike a critical hit with a melee attack on a creature, you regain hit points equal to the damage dealt, for an amount up to twice your fighter level.

Blood Tap

Also at 3rd level, you can harness your own blood to enhance your attacks. When you use your Second Wind, you can instead damage yourself for an amount equal to what would have been healed. This damage cannot be reduced in any way. After doing so, your weapon attacks score a critical hit on a roll of 19–20, for an amount of attacks equal to the number rolled. This effect is lost at the end of a short or long rest.

One Foot in the Grave

At 7th level, your body grows closer to that of your more vampiric kin, granting you certain defences. You gain resistance to necrotic damage, and immunity to poison damage and the Poisoned condition.

In addition, when you make a death saving throw, you succeed on a 9 or higher instead of a 10.

Blood Drive

At 10th level, your thirst for blood can overwhelm you, channelling your ferocity into your strikes. When you use your Action Surge and take the Attack with it, each creature you hit with a melee attack will take an additional 1d6 necrotic damage. You will then regain hit points equal to the amount of necrotic damage dealt. When you reach 17th level, the damage increases to 2d6.

In addition, you can add your proficiency bonus to your initiative.

Bloody Critical

At 15th level, your eternal cravings further intensify your strikes. Your weapon attacks score a critical hit on a roll of 19–20. When you use your Blood Tap, it lowers to a roll of 18–20.

Ravenous Predator

At 18th level, you act as a vicious monster on the battlefield, shedding your humanity to indulge your gory appetites. Your walking speed increases by 10 feet. As an action, you can make a bite attack against a willing creature, or one that is Grappled, Incapacitated, or Restrained. A creature struck by this attack will take 1d6 + your Dexterity modifier piercing damage, and 2d6 necrotic damage. Their hit point maximum is then reduced by an amount equal to the necrotic damage taken, and you regain hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.