Diregrizzlybear wrote an excellent adaptation of the 5e Raven Queen Warlock for B/X. I felt inspired, because I think the Raven Queen is by far the best warlock patron in 5e and it's a real shame they never made it official. So here's a GLOG adaptation of the B/X adaptation of the 5e adaptation.
Equipment: Any weapon (3 javelins counts as 1 weapon, ranged weapons come with 20 ammunition), a small silver bowl, 4 sticks of rare incense, a ritual dagger, and dark, concealing robes.
Skills: Occult Lore and 1d3: 1. Stealth 2. Haruspicy 3. Weaving
Servants of the Raven Queen gain +1 HP, +1 Stealth, and +1 Save vs Death every second template.
A: Raven Companion
B: Spellcasting, +1 MD
C: Mark of Death, +1 Spell
D: Psychopomp, +1 MD, +1 Spell
Raven Companion: The Raven Queen has graced you with one of her ineffable companions, which takes the form of a spectral raven. This raven can understand you and will obey your commands. You can see through the eyes of the raven and experience all its sensations at will, although you are insensate of your own surroundings while doing so. You can also merge your form with that of the raven at will by joining yourself to its shadow. The raven never sleeps, and while it is perched on your shoulder you have supernatural perception and cannot be surprised.
Spellcasting: You do not have to prepare spells; instead you can cast any spell you know at any time so long as you have MD available. You know two random spells from the first eight on the list, and gain one more at each further template of Servant of the Raven Queen (from the first 10 at C and all 12 at D). You can only get the requisite 3 MD for Dooms by multiclassing, so just use those Dooms if you do so.
Mark of Death: As an action, you can lay a Mark of Death on a creature you can see. The target takes +1 damage from all sources, you have +2 to-hit against the target, and the target has a -2 penalty to Saves you cause them to make. You know the location of the target at all times. This Mark can only affect one creature at once, and if you lay it on a new target, the old target is no longer affected.
Psychopomp: When you touch an undead creature with HD less than or equal to your level, they must Save vs Death or instantly die. If a creature succeeds on their Save, they are immune to this ability for 24 hours. Any corpse you touch can never be raised from the dead.
- Bestow Curse
- Starlight Lance
- Turn Undead
- Cloak of Darkness
- Consuming Shadows
- Crown of Stars
- Word of Death
- Take 1d6 damage
- Take +1 damage from all sources for the next hour
- Spectral hands seize and immobilize you for 1d6 rounds.
- You're besieged with a barrage of bad omens and dark predictions. Save vs Fear or panic for 1d6 rounds.
- All sentient creatures are invisible to you for 24 hours.
- All undead within 10 miles know your location unerringly and are driven to attack you for 24 hours. If there are no undead within the area, 2d6 random bodies rise as 1 HD zombies.