Black knights are a varied lot of supernaturally-empowered warriors firmly devoted to whatever gets the job done. Ruthless, cynical, and often nihilistic, they have a well-deserved dark reputation, but not every one of these warriors is a villain. However, none of them are particularly concerned with honor. The routes one takes to become a black knight are varied; some are indeed dedicated servants of evil, whereas others are merely masterless warriors for whom survival carries precedence over “proper” warrior codes. A few are even closet idealists, albeit bitter and jaded ones.
All black knights hold similar tenets, regardless of any master they serve.
Add the affliction school of magic to your list of herald spells.
At 3rd level when you choose this archetype, you gain the following two Channel Divinity options.
When you hit with a melee weapon attack, you can use your channel divinity to curse the wound (no action required). The target of the attack takes an additional 1d8 necrotic damage and must make a Constitution saving throw against your spell save DC. If the target fails, it cannot regain hit points until it finishes a long rest. If it succeeds, its maximum hit points are reduced by an amount equal to the damage done by your attack until it finishes a long rest.
You may perform an hour-long ritual to mark a suit of armor, and either a pair of weapons or a weapon and a shield. Thereafter, you may use your channel divinity as a bonus action to summon the marked items onto your body. The armor appears on your body and any weapon or shield appears in your hands. If you are wearing different armor or are carrying other items, they appear in a neat pile at your feet. This effect works at any distance, provided your marked items are on the same plane as you.
Also at 3rd level, you gain proficiency with your choice of combat tradition from either Mist and Shade or Tooth and Claw. You also gain a single rank one maneuver from the selected tradition that does not count against your known maneuvers.
Additionally, you gain proficiency with the poisoner’s kit and a single rare weapon of your choice.
At 7th level, your appearance, disposition, reputation, or some combination of the three unsettles even the courageous. You gain a passive Intimidation score. Creatures that are not already friendly to you that see you must make a Wisdom save against your passive Intimidation score. Creatures that fail this saving throw are daunted by your fearsome aspect.
A daunted creature acts in various ways depending on the situation and the Narrator’s discretion. Most non-hostile daunted creatures simply find somewhere else to be. Hostile daunted creatures might also excuse themselves (often making a show of bravado before doing so). A daunted creature that attacks you takes a -1d4 penalty to their attack rolls.
A creature engaged in combat with you can re-attempt their save against this effect at the end of each of their turns, ending the effect on a success. Creatures not in combat with you can retry the save every hour. A creature that successfully saves against this effect gains immunity to it for 24 hours.
Creatures that are immune to fear are also immune to your Menacing Countenance.
Also at 7th level, you are either dreadfully well-known or chillingly anonymous. You permanently raise or lower your Prestige score by 1 point.
Starting at 15th level, you have learned to tap into sources of power perhaps best left alone, lashing your injured foes with dark energies. Once per round, when you make an attack against a bloodied creature it takes necrotic damage equal to your herald level. This damage occurs whether the attack hits or misses, and is in addition to any damage from the attack.
Also at 15th level, you gain darkvision out to 60 feet. If you already have darkvision, its range extends by 60 feet instead. In addition to the normal benefits, you can see through magical darkness as if it were dim light.
Additionally, as an action, you may drop the light level within 30 feet of you by one step for up to 10 minutes. Bright light becomes dim light, dim light becomes darkness, and darkness becomes magical darkness. Once you have used this feature, you cannot do so again until you finish a long rest.
At 20th level, you fully become a terrifying figure out of nightmare and legend. You gain the following abilities: