From Compendium of Worldly Lore
The warrior of darkness, sometimes called the dark knight, is a practitioner of black magic. He studies the dark arts and learns the terrible secrets involved with evil rituals and spells. However, he does not cast spells himself. Instead, he uses his arcane knowledge to make himself a more formidable combatant.
Evil fighters, often those with a few levels of wizard or sorcerer, sometimes become warriors of darkness. Less frequently, warriors of darkness come from the ranks of single classed wizards or sorcerers, or bards, rangers, and even clerics. Warriors of darkness often keep to themselves, although they sometimes ally themselves with evil sorcerers or wizards.
Other times, they employ small groups of evil humanoids such as orcs, gnolls, and bugbears to aid them and guard their dark sanctums. They dream of power and conquest through violence and bloodshed. A warrior of darkness is not usually subtle, nor is he barbaric. Instead, he is a chilling compromise of physical might and intelligent sophistication.
Role: DPS
Characteristics: Augmented black magic toting warriors
Source: Book of Vile Darkness
Game Rule Information
The Warrior of Darkness has the following game statistics.
Abilities: Charisma for determining the potency of your black magic
Alignment: Any Evil
Hit Die: d10
Starting Gold: N/A
Class Skills
The Warrior of Darkness's class skills are Alchemy (Int), Bluff (Cha), Climb (Str), Con�centration (Con), Hide (Dex), Jump (Str), Knowledge (arcana) (Int), Knowledge (the planes) (Int), Listen (Wis), Move Silently (Dex), Ride (Dex), Scry (Int), Search (Int), Spellcraft (Int) and Spot (Wis).
Skill Points at 1st Level: (4 + Int modifier) × 4
Skill Points at Each Additional Level: 4 + Int modifier
Class Features
All of the following are class features of the Warrior of Darkness.
Weapon and Armor Proficiency: A Warrior of Darkness is proficient with all simple and martial weapons, all armor and shields except tower shields
Black Magic Oil Su: A warrior of darkness can use his forbidden arcane arts to create a magic oil that he anoints himself with. An individual warrior of darkness makes oil that works only on him, and he can only make one dose of the oil each time this class feature is gained (at 1st, 4th, 7th, and 10th level).
When he attains an appropriate level, the warrior of darkness creates a new black magic oil and anoints himself with it. He then chooses from the above list of supernatural abilities to imbue within himself permanently, picking a choice available to him based on his class level and Charisma modifier (the highest-numbered choice possible, or any lower one). A warrior of darkness cannot choose an ability more than once.
Darkling Weapon Su: With 3 rounds of preparation (involving rituals and alchemical substances that cost 50 gp), a warrior of darkness can imbue any weapon with a +1-enhancement bonus on attack and damage rolls. If the weapon already has an enhancement bonus, the warrior of darkness can instead imbue the weapon with any magical special quality that is the equivalent of a +1 bonus. The bonus or special quality only functions when the weapon is in the hands of the warrior of darkness, and it lasts 1 hour per warrior of darkness level. The warrior can imbue only one special quality in a weapon at a time.
Black Magic Elixir Su: At 3rd level, a warrior of darkness can use his knowledge of black magic and alchemy to create a magical elixir that he then imbibes. An individual warrior of darkness makes elixir that works only on him, and he can only make one dose of the elixir each time this class feature is gained (at 3rd, 6th, and 9th level).
When he creates an elixir, the warrior of darkness chooses from the following list of supernatural abilities to imbue within himself permanently, picking a choice available to him based on his class level and Charisma modifier. No ability other than violent knowledge may be chosen more than once.
Cleave, Deflect Arrows, Dodge, Exotic Weapon Proficiency, Combat Expertise, Far Shot, Great Cleave, Improved Bull Rush, Improved Critical, Improved Disarm, Improved Initiative, Improved Sunder, Improved Trip, Improved Two-Weapon Fighting, Improved Unarmed Strike, Mobility, Mounted Archery, Mounted Combat, Point Blank Shot, Power Attack, Precise Shot, Quick Draw, Rapid Shot, Ride-By Attack, Shot on the Run, Spirited Charge, Spring Attack, Stunning Fist, Trample, Two-Weapon Fighting, Weapon Finesse, Weapon Focus, Weapon Specialization, Whirlwind Attack.
A character can select feats Weapon Focus and Weapon Specialization more than once, but it must be for a different weapon each time. Characters must still meet all prerequisites for a feat, including ability scores and base attack bonus.
Scarred Flesh Su: Through ritual scarification, a 5th- level warrior of darkness gains damage reduction 5/+3.
Repellent Flesh Su: Through ritual, obscene tattooing, an 8th-level warrior of darkness gains spell resistance 20.