IMC, I decided to go for someting of a RuneQuest feel (in RQ, just about anyone can use /some/ magic, and real magic items are rare).
One rule I added was that Clerics didn't get Domains. Instead, anyone who was initiated into a cult could get Domains (including Clerics, of course). Thus, any character with an 11+ WIS could learn to use at least some Divine Magic.
I also overhauled the rules for creating magic items. Most significantly, any permanent item retains a link to it's creator that can be used to transmit spells through the item, to it's maker, and, if the maker dies, the item becomes non-magical. 'Power components' from the DMG circumvent that little problem, but they are, of course, conveniently under my control.
Here's the complete magic item overhaul:
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Item Creation:
In order to create an item, you must have the requisite feat, and meet all the prerequisites. You cannot use magic items to provide pre-requisites, nor use multifunction spells (like limited wish) or spell-like powers to immitate pre-requisite spells. When an item has a different 'form factor' but is otherwise similar to an existing sort of item, both creation feats are required. For instance, a sword that holds 50 charges of spell-triggered fireballs requires both Craft Arms & Armor and Craft Wand; a Cloak of Invisibility requires both Craft Wonderous Item and Forge Ring.
Formulae: Each magic item has a unique formula for it's creation, much like a spell. In the case of spell-completion items and potions, the formula is the spell - so all you need is the feat and the known spell. For any other item, you need to research the making of the item, like you would a new spell. Item creation formulae do not count against spells known.
Cooperation: Two or more casters can cooperate to produce a magic item, however, all those involved must have the apropriate item-creation feats. If a Power Component is not used, each participant must contribute at least 1 exp towards the exp cost of the item.
Experience expenditure: Spending experience on a magic item represents the creator infusing his own life force into the item. For charged items, the life-force is patterned into a specific effect that is only released later, there is no ongoing link with the creator, though it is often easy for a caster to identify the creator of a charged item by the 'signature' of his power. For non-charged items, the life-force is part of a continuous link between the item and its creator. The item remains magical only so long as the creator is alive or his soul/spirit is otherwise active in the material world. Because of the mystical link between the two, spells that target a creature can be cast onto the item to affect the caster, and object-affecting spells can be cast upon (or by) the caster to affect the item. There is no range limitation on such spell use.
Power Components: Some materials, in addition to being part of the cost of an item, also bring with them magical power sufficient to create the item without the caster investing his own life force (exp) into the item. Such materials are prized, as they allow genuinely permanent items to be created by a caster without the usual dangers. NPC item creators virtually always insist on being suplied with power components when commissioned to make an item.
Feats:
Scribe Scroll: The most straightforward item creation feat allows you to create spell-completion items. You need know only the spell to be scribed to use this feat, no item-creation formula is required.
Brew Potion: A favourite feat among Adepts, allows you to create a use-activated, single charge, item in the form of an elixir or oil that delivers a spell effect to the person imbibing or aplying it. In most cases, you need know only the spell to be placed in the potion to use this feat, no item-creation formula is required. Some unique potion formulae exist, however, that do not use normal spells, and these must be researched or found individually.
Craft Wonderous Item: Primarily used to allow more powerful feats to be aplied to a wider variety of items, by itself, this feat allows the creation of command-word activated items with limited uses (up to 5 times per day), that duplicate spells up to 3rd level, and affect only the user of the item or affect only the item, itself (as with a feather token or patch on a robe of useful items). Combined with other feats like Craft Rod and Forge Ring, the full range of Wonderous items can be created.
Craft Rod: This powerful feat lets the caster create command-word activated items that can evoke effects of any level up to 5 times per day. The effects of Rods are generally limitted to the user of the Rod, the Rod itself (changing it or making it act as a weapon), or those touched by or looking upon the rod. Offensive ranged effects are not generally possible, requiring a spell-triggered item creation feat like Craft Wand or Craft Staff.
Craft Staff: This powerful feat allows the creation of multi-functional, spell-trigger items of any level, with up to 50 charges. It can be combined with other creation feats to allow for overt high-level effects that can target others.
Forge Ring: Forge Ring is a powerful feat. Only rings, or items made by a creator with the Forge Ring feat, can contain permanent, continuous, use-activated spell effects. Other types of items must have charges or limitted uses per day (up to 5). Thus, many Wonderous Items, for instance, also require Forge Ring.
Carve Runes: Level 10: Create a re-useable Spell-Completion item, or a 'matrix?' Runes must be carved into a durrable item. Stone tablets, Metal rods, wands or staves, and jewels are commonly used. Jewels are called 'matrixes' and contain the 'shapes' of a spell within thier fascets. Carved runes are simply read to activate thier power and work one or more times per day. Reading runes is a least Standard Action that provokes attacks of oportunity, just like using a scroll. Matrixes must be infused with magical power to produce thier effects - the user releases the energy of a stored or potential spell into the matrix and the matrix's spell is cast in turn. Matrixes are greatly prized by Sorcerers. Feeding energy into a matrix is a Move Equivalent Action that provokes an Attack of Opportunity, and can be interrupted, and is subject to arcane spell failure, just like regular spellcasting. Directing the spell produced by the Matrix is a Standard Action that does not provoke an Attack of Opportunity. A character restricted to Partial Actions, can feed energy into a Matrix one round, and direct it's effect the next. The base cost of a rune spell is 500gp x caster level x spell level x the number of uses per day. The base cost of a matrix is 1000gp x caster level x spell level.
Craft Charm: Level 1: Charms are small polished stones, lucky pieces, or fetish pouches carried to ward off evil or grant good luck or enhanced skill. A Charm is a continuous, use-activated item that grants a +1 named bonus and does not take up a 'space' on the character. Though charms grant named bonuses, no two charms can add to the same roll - effectively, a charm bonus is named twice. For instance, a charm that grants a +1 to saves vs evil magic gives a 'charmed resistance bonus' and won't stack with a regular resistance bonus or any other charm bonus. The basic cost of a charm is based on the kind of bonus it gives, (doubled for not taking up a slot) but, most charms are restricted as to when the bonus aplies. Few charms, for instance, give a +1 charmed resistance bonus to all saves, most give thier bonuses vs only a specific danger. Charms can cost as little as 10% of normal cost if they are very restricted in aplication. Craft Charm can be used to make the ultimate charm: the Luckstone, which grants a +1 Charmed Luck bonus to all (d20) rolls, obviating virtually any other charms the bearer may carry. Unlike most permanent items, Charms can be made from comparatively commonplace 'power components' such as the claws of beasts, semi-precious stones, meticulously gathered herbs and the like. Such power components must be gathered by the creator of the charm, or the character for whom it is being created.
Activation:
Use-Activation: Craft Arms and Armor, Brew Potion, and Forge Ring allow the caster to craft items that are use-activated. Note that the first is limitted to enhancement bonuses and arms & armor enchantments, only, and that the second is limitted to spells that can target another (not those that only affect the caster) that are 3rd level and below, only. Rings and Potions generally only affect the user, unless an additional feat is used in thier creation. Arms and Armor enchantments generally only directly affect the enchanted weapon or armor, though, obviously, weapons can have considerable effects upon thier targets.
Spell-Completion: Scribe Scroll allows the caster to create spell completion items.
Spell-Trigger: Craft Wand and Craft Staff allow the creation of Spell-Triggered items. Craft Wand is limitted to spells of 4th level and lower.
Command-Word Activation: Craft Wonderous Item or Craft Rod can be used to produce items that are activated by a simple command word.
Usage:
Charges: Scribe Scroll and Brew Potion allow only the creation of single-charge items. Crraft Wand and Craft Staff allow the creation of items with up to 50 charges.
Uses per day: Craft Wonderous Item and Craft Rod allow the creation of items which can be used up to 5 times per day.
Continuous Use: Craft Arms and Armor and Forge Ring can be used to create items that function continuously, as desired. Craft Arms and Armor is restricted to creating enhancement bonuses and arms & armor enchantments.
Form Factor:
Each feat assumes the creation of a certain type of item. Brew Potion assumes that you will make a magical elixir that is to be drunk or aplied like an oil. Scribe Scroll assumes writing on some sort of portable medium. Craft Wonderous Item is the catch-all for forms not covered by other feats. The form-factor for the feat is assumed to be the one best-suited for the type of enchantments it permits. Thus, if you want an item that throws spell-triggered fireballs, a wand is the best vessel to hold the magic. You can also combine feats - both to combine the sorts of enchantments permiseable, and to allow alternative form factors. For instance, if you wanted magical gauntlets that let the wearer throw a bolt of lighting every round by merely clapping his hands, you'd have to combine Craft Wonderous Item (for the form), Forge Ring (use activated, unlimitted use) and Craft Wands (throwing an offensive effect of 3rd level or less).