Crush's ideas are a good starting point for my ideas, but the following list are my ideas:

Magic Energy

• Found in all living things, including you (mana)
• Found in large amounts in crystals

Runes

• Runes have a will (strength) that is how strongly they can pull mana out of their surroundings
• Runes like to chaotically release elemental energy (lightning, wind, fire) as soon as they absorb magic energy.
• Runes derive their will from the the will of the rune's crafter
• There is only one kind rune for each element type, not many.

Mana

• The character's mana auto-recharges
• The character's mana store comes from a combination of vitality, will, and intelligence

Intelligence

• Dexterity for spells
• The ability to strategically manipulate the discharge of a rune's energy--allows you to learn varying spell effects.

Spells

• You can't have multiples of the same spell--you can only increase the strength of a spell as you're casting, according to your will.

Will

• Will is the strength of player to control magical energy though mental exertion of will over it.

What happens

The relationship between the rune and your character is given by the formulas:

Ed(t) = Rw(t)-min(Cc(t),Cw(t))

where

 t = the moment in time
 Ed = the rate at which magical energy is absorbed by the rune and Elemental Energy Discharged (or vice versa)
 Rw = the Rune's Will (strength at pulling energies from your character and from other things around them)
 Cw = your Character's Will for containing its magical energy and resisting the rune's will
 Cc = your Character's total available magic energy Capacity store (mana) at any given time

Cw(t) = 0 when you cast a spell (when you want to let the rune draw your mana and discharge elemental energy). To be able to prevent the rune from drawing your mana, you must be able to equalize your Cw to match the Rw. The maximum possible value for ot change Cw to is your will.

• With no will, no intelligence:

Runes will endlessly suck magical energy from your mana and discharge the energy chaotically (not controlled, directed, or useful). Weapons with runes on them can still do damage bonuses, but the effect is subject to the will of the rune, which is usually uncontrolled and random, and it can damage you also.

• With will, no intelligence:

A greater will allows you to exert control over the rune--it lets you choose when to release its energy (cast it). A greater will constrains a weapon's rune and directs its energy discharge towards the intended purpose of the weapon. Once you have willpower, a sword with a fire rune inscribed will do what you want it to (damage your enemies) with more consistency in proportion to your will vs. the rune's will when you slash. A wand will direct a rune's energy to where you point it (picture a water hose, or a flamethrower, or a laser pointer). However, without intelligence, you can't learn any special or strategic skills in directing the fire of the sword or the wand. In the case of the sword, it simply burns the victim on strike.

• Will and intelligence:

You can not only tame the rune, but direct its energies--you can do tricks such as heating the sword to increase damage, giving burning slash marks to your enemies, or using your sword to cut ice, etc. Other examples of using intelligence include:

 * directing lightning towards specific targets
 * having fire only burn the door of a house, but not the house
 * making smoke signs with the clouds using wind

• master will and master intelligence:

Being able to completely command the element of the rune, you will be able to make:

 * fire burn ice
 * wind crush mountains
 * water cut stone

• when Cw > Rw

You will be able to absorb elemental energy through the rune, which will convert it to magical energy and feed it to your mana, at the rate of Cw-Rw, until Cc is maximized. Also, your intelligence will allow you to again dexterously control the absorbing powers of the rune, allowing you to control where its magical energy transfers to. This allows a setup that enables the use of runes to solve puzzles, unlock magic doors, etc.

Notes

Occupations/skills are time-consuming (taking hours of work) and boring and monotonous (making trips, buying, selling, waiting, clicking the mouse). Under no circumstances should one be forced to spend hours and hours, day in and day out, doing something boring, just to get good at a game. Consequently, rune-crafting should either be a mini-game or should take no time, and there needs to be a way for non-rune-crafters to buy runes they want.

Also, this proposal is open to some amount of adaptation, such as if you would rather use crystals instead of runes, to complement the back-story currently developed for the mana world.