Death Knight

You are a warrior necromancer who's magical might is fueled by those who have been slain in battle. You can draw on a creature's life force when they die to smite your enemies or store their soul in you to make sure they can not be reborn. You are a force to be reckoned with.

Life Force Drain

Starting at 3rd level you can smite people with the power of the dead. As a bonus action you can gain an additional 1d6 of necrotic damage on all attacks until the end of your turn. You have a number of uses of this feature equal to your proficiency bonus and you regain these uses when you take a short or long rest. Additionally when a creature with in 10ft of you is reduced to 0HP you can use a reaction to regain a use of this feature.

When you reach 10th level in this class the damage from this feature is increased to 2d6 necrotic damage.

Horrific Strike

When you reduce a creature’s HP to 0 or score a critical hit, all hostile creatures within 30ft must make a wisdom saving throw (DC 8+ proficiency + intelligence modifier) or become frightened of you. They can attempt the saving throw again at the end of each of their turns.

Magical Souls

Starting at 10th level while you still have at least 1 use of Life Force Drain all attacks you make count as magical for the purpose of resistance and immunity.

Death Barrage

Starting at 15th level when you use your reaction to regain a use of Life Force Drain, you’re infused with the energies of death and can immediately either move up to half your Movement speed or make a single attack as part of the reaction to regain a use of Life Force Drain.

No Coming Back

Beginning at 18th level when any creature within 10ft is reduced to 0 HP and you use your reaction to regain a use of Life Force Drain that creature cannot be resurrected by anything less than a true resurrection while you still live as you’ve drained a portion of their soul. In addition to that, whenever you use life drain to infuse your weapon you gain temporary hit points equal to twice your proficiency modifier. These last a minute or until lost but while you have them you gain resistance to necrotic damage and gain advantage on saves against magic.