Obeahs are a Variant Class from Advanced Dungeons & Dragons. Introduced in Dragon Magazine #251, as part of the Sesheyan article, Obeahs are variant shamans who focus on communing with and calling upon the spirits for direct intervention in the world of the living. Having an obscure appearance, and taking its name from a real-world Caribbean spiritual tradition means that, for obvious reasons, the obeah never appeared in any other edition of Dungeons & Dragons.
Mechanically, Obeahs require a minimum of 12 Wisdom and 12 Charisma to qualify for the class. They have the same Hit Points, Saving Throws, THAC0, spell bonuses and magical item creation abilities as Clerics, but they use the Wizard EXP-to-level table, and they cannot turn undead, attract followers, or found a religious stronghold.
Obeahs are limited spell-casters; they can only cast spells from the Spheres of All, Animal, Divination, and Summoning, as well as one additional Sphere of their choice - this is the only bonus sphere that they get.
What makes them special, however, is the Favors mechanic. By spending a round and making a Charisma check, an obeah can call upon the spirits to grant a Favor; they may invoke a number of Favors per Week equal to their level, with some favors consuming more than 1 favor to invoke, and/or requiring a specific level to attain. The favor only occurs if the Charisma check is passed, obviously.
When making a "Favors Check", an obeah gains a -1 bonus per level, but a +2 penalty for each favor attempted previously in the same day. DMs are encouraged to add addition modifiers to reflect the seriousness or whimsy of the situation, the needs of the tribe, and so forth.
Ancestral Prayer: Grant a single targe a +2 bonus to all attack rolls, damage rolls, saving throws and proficiency checks for 1 round. Costs 1 Favor.
Appear: Calls upon the spirit to make a visible manifestation. It can't actually do anything, or say anything, but it can be used to impress or distract. The manifested image lasts (5 rounds + 1 round per obeah level). Costs 1 Favor.
Endure: The obeah becomes immune to exhaustion for 24 hours, but must sleep for at least 12 hours after using this Favor. Costs 2 Favors to invoke and can only be invoked 1/week.
Hex: Applies a -2 penalty to all attack rolls, damage rolls, saving throws and proficiency checks for 1 round to a single target. Costs 2 Favors.
Guide: Calls upon a spirit to possess either the obeah or a volunteer. The possessed being gains 1 bonus level per 3 levels of the obeah invoking this Favor for the duration of the possession (1 round/obeah level), with bonus HP left vanishing when the possession ends. This Favor is immediately cancelled if the target engages in actions that are in opposition to the character of the spirit or against the tribe in general. Costs 3 Favors.
Delegate: The invoked spirit maintains a spell that otherwise requires concentration or direct control for a number of rounds equal to the obeah's level. Costs 3 Favors.
Lesser Manifest: The invoked spirit partially manifests in the real world, mimicking the stats of a Dust Devil and obeying the obeah's commands for 1 round/obeah level. Costs 3 Favors.
Reincarnate: As per the Priest spell of the same name. Costs 5 Favors.
Manifest: The invoked spirit enters the physical world more fully than it did with Lesser Manifest; it has the stats of an Air Elemental, but cannot form whirlwinds. It obeys the obeah for 1 round/obeah level, but will not turn on them like a "real" air elemental - though it won't obey orders that oppose its desires or endanger the tribe. Costs 6 Favors.
Messenger: The obeah can send a short (100 words or less) message to any being on the same plane whose location they know and who is not shielded behind a magically protected or isolated location. Delivery occurs in 1 turn per league between the obeah and trhe recipient. Costs 7 Favors.
Request: Mimics the effect of a Limited Wish spell. Costs 9 Favors and can only be invoked 1/month.
Curse: Afflicts a single target with a Curse unless they pass a Save vs. Spell. Costs 10 Favors.
Greater Manifest: Calls forth a spirit to fulfil a single command, using the stats of an Aerial Servant. Costs 12 Favors.
Fulfillment: Mimics the effects of a Wish spell. Costs 14 Favors and can only be invoked 1/year.