I must confess that warlocks are (at least conceptually) my favorite DnD class. 'orrible users of magic are pretty much the best. However, their implementation has historically been pretty lacking. I've also been thinking about graduated levels of success, and realized that such a thing already exists in DnD and retroclones: the reaction table.
This combines well with the idea of warlocks cutting Faustian deals with powerful beings, rather than having Something Bad happen before character creation that lets them shoot devil lasers (not that I have a problem with whizz-bang magic. It just doesn't seem to fit). Using the reaction table gives GMs a framework for how the patron should deal with their client, rather than sitting backstage all the time.
A class for LotFP
HP and Saves as Cleric, XP as Fighter
Warlocks do not memorize spells like Magic-users. Instead, they forge pacts with spirits and use their power. All spirits have a domain (such as Ice or Love or Law), which dictates the kind of power and knowledge the possess. The pact is mutually beneficial; the Warlock gains access to magical knowledge and ability, while the spirit uses the Warlock to grow in power and intervene directly with mortal affairs.
Spirits have the innate ability to answer questions about their domain; a spirit of ice instinctively knows what and who is buried in an avalanche, for example, and a spirit of fire can know what a person looked like simply by examining their ashes. Their grasp of magic is not quite as strong; they can cast any spell that pertains to their domain, but must first encounter it. Warlocks often serve this purpose and can claim spells much like the way Magic-users can inscribe them in spell books. Claiming a spell requires a ritual that takes a number of hours equal to the spell's level, and once it is complete, the Warlock can assign it to a contracted spirit with an affiliated domain. Warlocks can claim spells of any level.
A Warlock can maintain a number of pacts equal to half level, rounded up. However, a Warlock has direct access to only one spirit at a time; if they wish to change which contracted spirit they may summon, they must complete an 8 hour ritual in a place of relative safety and reclusion. If a Warlock wants to forge a pact with a new spirit, they must find one in the course of play.
When a Warlock wants their contracted spirit to answer a question or cast a spell pertaining to its domain, they spend a turn summoning it, and the player makes a 2d6 Reaction roll with a bonus equal to half the Warlock's level, rounded down, and a penalty equal to the spell's level.
At this point, the Warlock must convince the spirit to cast the spell or answer the question. How much work this takes depends on the spirit's Reaction. If it is Cooperative, it requires nothing at all. If it is Interested, it might take a turn to cajole it into helping. If it is Annoyed, major bribes or favors might be necessary--one quarter of the silver pieces necessary to reach the Warlock's next level (so 500 sp at level and 4,000 sp at level 4) or a session's worth of adventuring, usually of an ethically dubious and/or legally questionable variety, to acquire an artifact, slay a rival, or perform some other dangerous task for the spirit is generally enough. Warlocks take a -1 penalty to Reaction rolls with a spirit for each favor they owe. Spirits are greedy, venal, and prideful, but they are not stupid. If a Warlock continually offers services but never performs them, the spirit will demand prices that can be paid immediately. Malicious spirits will completely enter the physical world and attack, but will often surrender before being defeated.
The HD of a spirit equals the Warlock's level plus the highest level spell they know, and they deal d6+level damage in melee, plus any other special abilities the GM deems appropriate. Existing in the physical world is exhausting to spirits, and so they can cast each spell they know only once before needing to return to the aether to rest. Spirits will enter the physical world to fight for Warlocks, but will do so only for a major favor, regardless of Reaction, and only to complete a specific, pre-determined task. Spirits in the physical world reduced to 0 HP must rest in the aether a number of days equal to their Warlock's level.
A level 1 Warlock begins play with a single spirit with a domain of their choice and a relevant, 1st level spell. Here's a sample spirit:
Atri-Rathma, Entwined Divinities of Love and Spite
Begin with Charm Person and can acquire any spell that pertains to mental manipulation and domination, such as Suggestion or Forget. Can answer questions about someone's love life, if an act was motivated by revenge, or anything pertaining to love, lust, and spite. They are fawning and flirty when in a helpful mood and sarcastic and deceptive while in a bad one.
- Help a star-crossed couple from the nearest village escape from their disapproving families and start a new life in the nearest city. There is a 50% chance the relationship is clearly headed for disaster.
- The constabulary force of the nearest city is about to shut down a brothel. For purposes of blackmail, Atri-Rathma wants you to plant evidence in the captain's home that suggests he frequented the brothel himself.
- Help a woman from the second-nearest city murder her abusive husband, who recently humiliated her in a public affair.
- Acquire the Liqueur of Atri (a staggeringly powerful aphrodisiac), which is currently being guarded in the nearest temple of the stodgiest local religion, and return it to Atri-Rathma.
- Acquire the Liqueur of Rathma (an exquisitely deadly poison), which is curently being guarded in the nearest temple of the shadiest local religion, and return it to Atri-Rathma.
- Fund a wild bacchanal (must cost at least 25% of the silver pieces necessary to reach the next level) in the nearest city.
Batrabos, Grim Demon of Law
Begins with Command and can learn any spell pertaining to subjugation, imprisonment, and order. Can answer questions about legality, technicality, and jurisprudence. He is all patient patriarch when he's helpful and BOOMING THEATRICALITY when he's mad.
- Hunt down an escaped fugitive d6 miles from your location. There is a 50% chance he was convicted on a technicality.
- Kill a member of the nearest city's constabulary, who has been accepting bribes from the biggest gang in town.
- Acquire and destroy the Oneiric Needle (a powerful device of disorder), located in a cult hideout not far from the nearest village.
- Acquire the Hircine Lance, a weapon created from one of Batrabos' horns, and return it to him.
- Clear a shrine belonging to one of Batrabos' fallen sisters of the brigands that have taken up residence in it. It is located close to the nearest city.
- Fund an inquest into a decades-old cold case (must cost at least 25% of the silver pieces necessary to reach the next level) in the nearest city. 4 in 6 chance it find a culprit, and on a 1 it is someone important.