sorry for length
Depending on the nature of the campaign, divine casters may need a slight adjustment or a major overhaul. Personally, I'm generally inclined toward the latter, given how the idea of a cleric does not mesh with the mechanics supporting it. Here are a few things I'd likely do:
1. Reduce the basic combat abilities of divine casters. Like primary arcane casters, divine casters would get a poor BAB, similar saves (Will good, Fortitude and Reflex poor), no armor or shield proficiencies, and only simple weapon proficiencies to start with. Their HD would be d6. If the player wants more martial abilities, they can choose martial deities (or--gasp!--multiclass with a more frontline class like barbarian, fighter, or paladin).
2. Clerics have more limited spells known, determined by the deity's domains and their Wisdom score. Clerics automatically know the spells given by the deity's domains, and can cast them spontaneously. Anything extra is like a divine favor granted to the most promising of the deity's followers and is based on the Wisdom bonus. Clerics can have a number of extra known spells equal to their Wisdom bonus, with a maximum level equal to the maximum level of the spell the cleric can cast at any given level. These extra spells are chosen from the generic cleric spell list, and the alignment restrictions still apply. Enhancement bonuses due to magic items and spells do not alter how many of these extra spells you know, since they come from the gods, and they grant these benefits based solely on the worth of the individual, not the power of his or her gear.
3. Druidic armor and weapons proficiencies are altered to better fit the concept of a divine caster who reveres and protects nature. They may only use weapons that can double as tools. Sickles thrash wheat but can also fend off an attacker. Daggers cut hide and meat but can rupture a man's liver as well. A hatchet chops firewood as easily as limbs. Unless a particular weapon is forbidden to them, druids are proficient with all simple weapons, the handaxe, and the net. They avoid using items that are solely instruments of war or industry because they believe that industry, especially as enhanced through the war machine, upsets the balance of nature far too much. Druids are thus forbidden to use weapons specifically designed for war, such as swords, battle axes, polearms, and most exotic weapons. They are not proficient with any armor or shields, but the ones they do wear are generally made of organic materials or taken from those that no longer need it (ie, looted from corpses).
4. Druids must uphold vows to keep their powers (replaces the "any neutral" alignment requirement). If they break these vows, they may regain them by performing appropriate acts of atonement. This cannot be circumvented or short-cut by a spell, not even
wish or
miracle. The druidic vows are:
- Save a life to take a life. This vow prohibits killing for sport or material gain, for doing so violates the sanctity of life. Killing is permitted only in self-defense or to procure food. Of course, definitions vary on what self-defense means. Some druids see the destruction of budding cities as defending their own homes. And when it comes to feeding themselves, cannibalism is not unheard of. Even in these circumstances, steps must be taken to replace the loss of life, to maintain the balance of nature. This includes planting new trees to replace ones that have been cut down, protecting young animals until adulthood when a healthy animal has been slain, and giving the material profits of a party member to those who need it most. In the case of abominations like undead, this rule no longer applies. Most druids feel compelled to destroy these unnatural horrors as soon as possible.
- All things in nature live by virtue of their own strength, cunning, and skill; so must you. To the druids who live in rural or wild lands, urbanites seem disconnected from the process of life. Very seldom do they provide for their own needs. Farmers grow and harvest their food. Butchers slaughter the animals that provide their meat. Nurses tend to their sick. Smiths craft the armor and weapons that protect them. Tailors make their clothes. Morticians bury their dead. Some even have servants to do work they feel they can't be bothered with. Druids, on the other hand, prefer the independence and self-reliance that come from living with nature, not shirking labor simply for the sake of convenience. As much as possible, druids live by their own strength, skill, and luck, even (or rather, especially) if that means they have to learn new things to do so. This does not mean they refuse the help of other members in the party if it is needed, or that they do not help others who need it. Rather, it means that they don't do so simply because it is convienient.
- Take only what you need and leave the rest. Accumulating wealth and material goods for their own sake is antithetical to the druidic worldview. Nature provides all we need. Why ask or demand more? This is not to say druids are prohibited from making long-range plans, using accumulated wealth to a specific end that benefits nature. For example, a druid can adventure to earn enough money to purchase land, thus protecting it from those who would destroy it.
- Death is a part of life. It is the ultimate symbol of hubris to attemt to reverse death. Druids may not be resurrected or raised, nor will they directly contribute to raising or resurrecting a dead character. This does not mean that they do not protect and support their allies on what they see as a fool's errand, but they will not otherwise help in doing something so opposed to their values.
5. Instead of relying on the PHB deities for clerics, I'd do something else that allows for more flexibility and creativity. In lieu of using standard Greyhawk gods, players and DMs can create their own gods and assign the proper aspect(s). Instead of being actual deities, aspects are basically the concepts that a deity has dominion over. These are the alignments, domains, and favored weapons associated with each aspect I've made up so far:
- Death (N): Death, Destruction, Law/Chaos (choose one), Travel. Favored weapon: scythe
- Fate (N): Knowledge, Luck, Protection, Trickery. Favored weapon: none (though longsword can work)
- Justice (LN): Destruction, Knowledge, Law, Protection. Favored weapon: longsword
- Life (NG): Animal, Healing, Plant, Sun, Water. Favored weapon: none (though quarterstaff can work)
- Love (CG): Good, Knowledge, Luck, Protection. Favored weapon: (composite) shortbow
- Moon (N): Healing, Magic, Trickery, Water. Favored weapon: sickle
- Mountain (LG): Earth, Law, Protection, Strength. Favored weapon: war hammer (or pick)
- Nature (N): Animal, Death/Destruction/Healing, Plant, Sun, Water. Favored weapon: quarterstaff
- Peace (NG): Good, Healing, Luck, Protection. Favored weapon: none
- Sea (CN): Air, Luck, Travel, Water. Favored weapon: trident
- Storm (CN): Air, Chaos, Destruction, Strength. Favored weapon: flail
- Sun (LG): Fire, Healing, Sun. Favored weapon: mace (or morningstar)
- Torment (NE): Death, Destruction, Evil. Favored weapon: scourge
- Trickery (CN): Chaos, Luck, Magic, Travel, Trickery. Favored weapon: rapier (or whip)
- Valor (LG): Law, Protection, Strength, War. Favored weapon: any sword, axe, or polearm (choose one)
- War (CE): Chaos, Death, Destruction, Strength, War. Favored weapon: any sword, axe, or polearm (choose one)
- Wisdom (NG): Good, Healing, Knowledge, Magic. Favored weapon:
6. Spread abilities out across levels, granting boons particularly at some of the levels where you gain neither bonus feats nor ability increases. The following levels are critical in this regard: 2nd, 5th, 7th, 10th, 11th, 13th, 14th, 17th, and 19th. I'm tempted to allow the class abilities be one, some, or all of the following: additional domain boons, bonus domain (from domains appropriate to the deity), or a bonus feat chosen from a limited list (Combat Casting, Diligent, Iron Will, item creation feats, Leadership, metamagic feats, Negotiator, Persuasive, Self-Sufficient, Spell Penetration (Greater Spell Penetration), or Weapon Focus (deity's favored weapon) to name some).
7. Remove turn/rebuke undead from the generic cleric's abilities and make them domain abilities for clerics with the Good/Healing (for turn) or Death/Evil (for rebuke). A more potent ability would be able to turn or rebuke infernals and/or similar outsiders, but that's for higher (or even epic) levels.