Some additions to my latest post:
1: Quests. Person X needs a spell that does this, pays 100 gold for a copy.
2: Custom spells can be sold. Its power determines the cost as well as reputation and elements used in a spell and the combination of elements.
3: Shops sell stocks of paper that you need to write spell onto.
Note that magic is energy and that magic is instinctive. During battle you cannot be standing still reading a spellbook. Right now there are 2 ways. In DD you have mana and you rest when it is depleted. In Baldurs Gate you rest to prepare your spells.
But both systems are not really real. What spell you remember before sleep...and how does that work anyway, you learn as you sleep?...what spell do you need as you wander around town not knowing what mess you get into?
On the other hand, the mana system is similar to my system where you have just energy that depletes as you cast. Which is not to be mistaken for the 5 elemental energies you are able to use to create spells. The first is just your magical stamina, like mana. The second energies are the building blocks of spell energy and the categories of spells. The maximun water energy you can use depends on your level. And perhaps even how often you use water based magic. TGhis way you become a specialised mage.
4: To add to the spell system and make it more real you can add another factor which is a reagent of some type. Herbs and potions could be dragged into slots. A potion is like a spell and it has its effects like a spell. magical stones, amulets and any other special item could be used and sacrificed to create a spell. I don't see why it would not be possible with enough exp. levels to drag a sword or any weapon in a slot and add magical properties to it. perhaps this could be a special skill you need to learn or be granted by a master magical blacksmith.
I can see a Blade of the Floods that, when wielded, splashes water in the face of an enemy. Doing x water damage. So basically you write your spell and weapon combo to your spellbook.
The options are endless. You could even scarfice a weapon in the way that it will have 10 charges and then break and becomes unuseable.
Or why not make a sword that does electrical damage the amount of maximum energy at your disposal. One blow will deplete ALL your mana or magical energy but will also do tremendoes damge. it will also destroy the blade! handy in boss monster fights.
With this system near anything is possible, don't you think?
Anyone wanna make a game?