Sanguine Warrior

Blood Influence

When you choose this archetype at 3rd level, you can learn the cantrip Spare of the dying or chill touch. At 7th level you learn Life Transference or vampiric touch at 15th level you learn Hold Person or charm person and at 18th level you learn Death ward or Shadow of Moil which each can be cast once per day or by expending hit die equal to double the spell level and taking damage equal to the total roll of expended hit die (cannot be reduced).

Bloodcasting Ability

Constitution is your bloodcasting ability for your blood spells. You use your constitution whenever a spell refers to your bloodcasting ability. In addition, you use your Constitution modifier when setting the saving throw DC for a blood spell you cast and when making an attack roll with one.

Bloodcasting save DC = 8 + your proficiency bonus + your Constitution modifier

Bloodcasting attack modifier = your proficiency bonus + your Constitution modifier

Vile Cut

Starting at 3rd level, your blood becomes connected with your weapon, being able to cause harm to others who are tainted with it.

During a short rest, you can choose one non-magical weapon you are proficient with, this weapon becomes your Blood Pact weapon. Your Blood Pact weapon is considered magical for the purpose of overcoming immunity and resistance to nonmagical attacks and damage. This weapon cannot be disarmed from you and you know the location of this weapon at all time, as long as it is with in the material plain.

At 10th level you can choose a magic weapon for your blood pact weapon, it cannot leave your person by any means and you know its exact location of this weapon at all times.

In addition, each time you make an weapon attack with your Blood Pact weapon, you can expend one of your hit die and take 1d6 necrotic damage, this damage cannot be reduced in anyway. The target of this attack, takes damage equal to the roll of your expended hit die. 

You can expend more hit die when you reach certain levels in this class, two hit die at 7th level, three hit die at 10th level, four hit die at 15th level and five hit die at 18th level.

You regain all your expended hit die on a long rest.

Half Blood Frenzy

Starting at 7th level, when you are hurt, your veins pump with adrenaline, causing mass panic to those nearby as you bloody your enemies. When your total hit points are reduced to half or lower, you become half blood frenzied, gaining additional benefits;

• When you attack with your Blood Pact weapon, you gain a bonus necrotic damage equal to your constitution modifier and you ignore any resistance that involves necrotic damage.
• You have advantage on constitution saving throws. 
• Whenever you reduce a creature to 0 hit points with your Blood Pact weapon, you can force each creature with in 5 feet of the target to make a Wisdom saving throw, and if the saving throw fails, the target(s) is frightened of you until the end of your next turn. The saving throw goes against your blood save DC.
• You have advantage on intimidation (charisma) checks.

Blood Transfusion

Starting at 10th level, you find the resourcefulness in the blood of your enemies. 

Once per turn, whenever you hit a creature with your Blood Pact weapon, that isn’t a Construct or an Undead, you regain hit points equal to two rolls of your hit die or you can regain one expended hit die instead. If the target is a construct or undead, roll two hit die, add the total roll to this attack as necrotic damage.

In addition, if you use the second wind bonus action, you can forgo the heal and instead regain hit die equal to half your fighter level (rounded down).

Sanguine Blade

Starting at 15th level, your Blood Pact weapon becomes increasingly potent.

Whenever a creature successful hits you with a weapon or spell attack, you can use your reaction to change your Blood Pact weapon into a Sanguine Blade. Sanguine Blade has the range of 30 feet and lasts until your next successful attack with it. On hit, you deal double your weapon die as necrotic damage and you can force the target of the attack to make a constitution saving throw. On a fail, the targets total hit points is reduced and cannot be healed for 1 minute, other than the greater restoration or wish spell. The reduced health is equal to (proficiency bonus x hit die). If the target is frightened of you, it has must roll its saving throw at disadvantage. The saving throw goes against your blood save DC.

You can use Sanguine Blade a number of times equal to your constitution modifier (a minimum of once), and you regain all expended uses of it when you finish a long rest.

Full Blood Frenzy

Starting at 18th level, you are a master of manipulating your blood, creating even stronger connections with your body and weapon. You gain access to Full Blood Frenzy, allowing an even stronger Blood Frenzy. When your total hit points are reduced to half or lower, you become full blood frenzy, gaining the benefits of half blood frenzy plus the following;

• As a part of your Sanguine Blade reaction, you can expend five hit die, taking 50 necrotic damage, which cannot be reduced in anyway. On your next Sanguine Blade attack, the target of that attack suffers an additional 50 necrotic damage, and cannot regain hit points until the end of your next turn.
• When you attack with your Blood Pact weapon, you ignore any resistance and immunity to Necrotic damage.
• Whenever you make a constitution saving throw, you can treat a d20 roll of 9 or lower as a 10.
• When a creature fails it's Wisdom saving throw to become frightened, the creature is instead paralyzed until the end of your next turn.