Here's an attempt at a warlock class, using as inspiration Scott Ludwig's class templates and a very similar implementation by Gianmatteo Tonci (this one is in Italian).
4E classes in OD&D: Warlock
by Giampaolo AgostaPrime Requisites: Constitution and Charisma (This mirrors the 4e primary scores, Con and Cha)
Other Requirements: Intelligence 9 or better (This maps the 4e requirement of Intelligence as the secondary score for all Warlock builds)
Experience Bonus: 5% for Con or Cha 13 or better; 10% for Con or Cha 15 or better, and the other 13 or better (Mirrors the need for a single score to be high, while the other will usually be lower).
Hit Dice: 1d4 per level up to 9th level. Starting with 10th level, +1 hit points per level, and Constitution adjustments no longer apply. (As Wizard. The Thief or Cleric setup could also be used, especially if the alternate version of spellcasting is used)
Maximum Level: 36.
Armour: Leather armour only; shield not permitted. (As Thief. Basically, that's what Warlocks get in 4e as well)
Weapons: any one handed small melee weapon, any two handed medium melee weapon; any small missile weapon. (Rationale: Warlocks should have a wider range of weapons than wizards, but not as large as Thieves)
Special Abilities: Magical Spells, Eldritch Blast. (No pact boon, prime shot, shadow walk or warlock's curse, since OD&D spells give more flexibility than 4e spells, and the corresponding features of Rogues don't exist for OD&D Thieves as well).
Experience Table: As Magic Users, spell progression x0.75 round down (alternate: as MU of 2/3 level; the former matches the 3 points magic ability in Gianmatteo Tonci's work, while the latter matches the same level in Scott Ludwig's templates).
Saving Throws: As Magic Users.
Combat: As Thieves. (This is needed both to cover the expanded combat role of Warlocks and the Eldritch Blast power)
Eldritch Blast
This class feature is modelled as a weapon mastery: you need to roll to hit against the target's AC, and can use the blast as any other missile weapon (i.e., once per round). No weapon is necessary to use it, though. It mirrors the at-will spells of 4e. Apply Con or Cha bonuses to the hit roll.
Primary: All. Defence: Nil.
| Mastery | Damage | Range | Special |
| Basic: | 1d6 | 40/80/160 | -- |
| Skilled: | 1d8 | 40/80/160 | Delay (s) |
| Expert: | 1d8+2 | 60/110/170 | Delay (s/m) |
| Master: | 1d10+3 | 60/110/170 | Stun (s), Delay (m) |
| Grand Master: | 1d12+4 | 80/130/180 | Stun (s/m) |
Rationale for some choices: range is 10 squares in 4e, which is equivalent to a sling short range. I gave it the full set of ranges of an OD&D sling, though it is possible to use only the short range to get a closer match. Damage is more or less like a bow or crossbow, since it should be about the best missile weapon available to the Warlock. There is no defence bonuses, and no to hit bonus from magic weapons, since the character is not holding a weapon -- rods or wands may give bonuses as in 4e, but in that case you would need a different mastery (e.g., club) to get a defence bonus. I've added delay and stun as specials, even though the Eldritch Blast doesn't have a special effect in 4e -- this should mirror the impairing effects of the Eyebite and Dire Radiance at-wills of 4e. Finally, primary is set at all to compensate for the lack of defence.
Spell list:
The spell list is a subset of the Magic User list, plus some Faerie magic and spells from various GAZs and HW sourcebooks. Many of these are not entirely appropriate, and could be replaced by conversions of the 4e powers or by custom spells.
First Level
Charm Person
Detect Magic
Darkness
Faerie Lights (GAZ5)
Longstride (GAZ5)
Dying Gasp (HWR3)
Protection from Evil
Read Magic
Second Level
Continual Darkness
Detect Evil
Detect Invisible
Invisibility
Levitate
Nightwatch (GAZ9)
Rot (GAZ9)
Fear (GAZ5)
Third Level
Clairvoyance
Dispel Magic
Fly
Hold Person*
Infravision
Invisibility 10' Radius
Sunstrike (HWR3)
Assume Gaseous Form (PC1)
Fourth Level
Charm Monster
Confusion
Dimension Door
Polymorph Other
Remove Curse*
Wizard Eye
Displacer Field (CoM)
Steal Breath (HWR3)
Fifth Level
Contact Outer Plane
Feeblemind
Hold Monster*
Magic Jar
Passwall
Polymorph Self (MU4)
Distance Distortion (HWA1)
Obliteration (HWR3)
Sixth Level
Anti-Magic Shell
Death Spell
Disintegrate
Geas*
Projected Image
Flesh to Stone
Disguise (DotE)
Teleport (MU5)
Seventh Level
Charm Plant
Magic Door
Mass Invisibility
Power Word Stun
Summon Object
Statue
Teleport any Object
Spell Turning (GAZ12)
Eighth Level
Clone
Dance
Mass Charm*
Mind Barrier*
Polymorph Any Object
Power Word Blind
Symbol
Travel
Ninth Level
Gate*
Immunity
Maze
Power Word Kill
Shapechange
Sleep-Curse (DotE)
Survival
Timestop