Blood Hunter

Throughout the land many evils ravage the innocent. Some choose to live in the path of light, earning the favor of the gods and earning access to there powers in order to combat this evil. Tragically some  are drawn to much darker paths. The Blood Hunters started as an order attempting to succeed where the churches before have failed. Now they are spread out or working alone, through out their motivations and methods remain the same. Using foul rituals the blood hunters amplify there own power so they can fight. Sadly there methods are not perfect and it take a toll on the individual Blood Hunter. That toll is what defines them

Becoming the enamy

In order to slay the most wretched and vile creature blood hunter ongo rituals to amplify there powers. From 3rd level and forword when your spellcasting feature let's you learn a new ranger spell of 1st level or higher, you can choose the new spell from the warlock spell list, in addition to the ranger spell list. You must otherwise obey all restrictions for selecting the spell, and it becomes a ranger spell for you.

Blood smites

In order to deal heavy blows against their enemies, blood hunters have learned themselves to sacrifice their own vitality in order to unleash their own wrath upon their foes. Starting at 3rd level when you hit a creature with a weapon attack, you can choose to expend one spell slot and 5 hit points to deal necrotic damage to the target, in addition to the weapons damage. The extra damage is 1d6 for a 1st level spell slot, plus 1d6 for each level after 1st. This damage increases at 7th level to 1d8, at 11th level to 1d10, and at 15th level to 1d12

Blood Rush

Starting at level 3 when you choose the archetype, you  learn to thrive on the death of your enemies. When ever you reduce a hostile creature to 0 hit points, you can spend one hit die to heal yourself. Roll the die, add your consitution modifier, and regain a number of hit points equal to the total (minimum of 1)

Blood Ritual

Beginning at 7th level, you have learned to recover your magical energy by undergoing a blood ritual. During a short rest you can choose to recover a used spell slot at the cost of your own hit points. You take 5 times the spell slots level necrodic damage, this damage cannot reduced or avoided. Additionally you become immune to the frightened condition 

Cursed Blood

At 11th level your blood becomes cursed by a combination of many rituals. Whenever you damage an opponent with a blood smite they have to man a con saving throw agents your spell save DC and if the fail they suffer from the poisoned condition for 1 minute. In addition your blood smites ignore immunity to necrodic damage, the damage is still halved if the target has resistance. You also gain the ability to spray your opponents blood in a 15 foot cone, this costs and deals the same damage as your blood smite, including the other effects of cursed blood.

Wretched Soul

At 15th level you have lost all respect for your own mortality. You have advantage on death saving throws and if you are stabilized after being knocked down to 0 hp, you can choose to get back up with 1 hp and one additional point of exhaustion. You have also realized that the damage you deal yourself during your blood smites can be replaced with an opponents blade. Whenever you are hit with a melee attack you can spend your reation to strike back, even if you are brought to 0 hit points or under. If this attack would trigger your blood rush feature you may also use that before going unconscious.