Blood knights were an ancient order of warriors who willingly endured a profane ritual of drinking vampire blood in order to gain supernatural combat prowess. Terrors on the battlefield, blood knights gained a reputation as fearsome warrior who hunted their foes relentlessly, shrugged off mortal blows, and who grew stronger with every person they killed. Eventually, the order was destroyed, but ancient texts and forgotten practitioners still instruct those willing to learn the dark path of blood power.
3rd-level blood knight feature
You are a relentless opponent in combat, striking with relentless fury. When you make a melee attack, you can mark your target. Until the end of your next turn, any opportunity attack you make against the target has advantage. The opportunity attack doesn't expend your reaction, but you can't make the attack if anything, such as the incapacitated condition or the shocking grasp spell, is preventing you from taking reactions. You are limited to one opportunity attack per turn.
3rd-level blood knight feature
You gain vitality with every creature you kill. When you reduce a hostile creature to 0 hit points, you gain temporary hit points equal to your Constitution modifier + your Fighter level (minimum of 1).
7th-level blood knight feature
Your reflexes and speed are enhanced by your vampiric power. You can take a bonus action on each of your turns in combat. This action can be used only to take the Dash or Disengage action.
10th-level Blood knight feature
Your connection to your vampiric heritage begins to allow you to ignore the biological needs of your body. You gain resistance to necrotic damage, and you don't need to eat, drink, or breathe.
15th-level Blood knight feature
You very gaze inspires dread in a foe. As a bonus action, you can fix your gaze on a creature you can see within 30 feet. If the target can see you, the target must succeed on a Wisdom saving throw against a DC equal to 8 + your proficiency bonus + your Constitution modifier or you gain advantage on attack rolls against the target. The effect lasts until the target takes damage or until the start of your next turn.
If a creature can’t be charmed, it is immune to this effect. A creature that successfully saves against your gaze is immune to it for 1 hour.
18th-level Blood knight feature
Your body has become like that of the living dead, with unnatural resistance to normal weapons. you gain resistance to bludgeoning, piercing, and slashing damage from nonmagical weapons.