Hexblade

Hexblade
Nobody is quite sure where the first hexblade came from, but most people in respectable regions are happy to blame Ramdrant's dark sorcerers for their existence. Wielding magic that is ethically sketchy at the best of times and outright dastardly in their hands, hexblades tend to revel in the havoc wrought by their most baleful curses. Everyone else just puts up with the cackling and hopes they go away soon.

Black Blade
Hexblades may be infamous for their proficiency in vile curses, but they are most instantly recognizable for the ebon blades that many of them wield. Beginning at 8th level, you add Bestow Curse and Hex to your list of spells known. These spells do not count against your usual limit of spells known. When you cast one of these spells, you can choose not to consume a spell slot in the casting. You can use this ability a number of times up to your Charisma modifier between long rests. Additionally, if you have the ability to summon a pact weapon, you can channel baleful energy through its strikes. As a bonus action, you can cast Bestow Curse on a creature you have damaged with a weapon attack using your pact weapon this turn.

Maleficant Magus
A Hexblade has no qualms with preying on the weak. In truth, their vile magic is specially harmful to those already ailing in body and soul. Beginning at 13th level, you gain Advantage on attack rolls made against creatures under the effects of a spell you have cast, and creatures at 50% or less of their maximum health suffer Disadvantage against spells you cast.

Killing Curse
It is said that Hexblades were born when a bored warlock compiled a vast tome of everything bad that can happen to a person, and decided to use it as a checklist. Beginning at 18th level, as an action once per long rest, you can issue the most dreadful of curses upon a single foe. The target must make a saving throw against your warlock save DC for each of their six ability scores, and suffers effects based on the number of these saves they fail. All effects are cumulative. At the end of each of their turns, the afflicted creature may make a saving throw using any of the ability scores they have not yet succeeded on a save with. A successful save reduces the magnitude of the effect to one requiring one fewer failed saves. A failed save does not worsen the effect beyond its initial application.
 * One Failure: The afflicted creature suffers Vulnerability to all damage.
 * Two Failures: The afflicted creature is Frightened of you.
 * Three Failures: The afflicted creature is Blinded.
 * Four Failures: The afflicted creature is Paralyzed.
 * Five Failures: The afflicted creature suffers Disadvantage on all saving throws, including those made against this ability.
 * Six Failures: The afflicted creature instantly dies a horrible, horrible death.