I realize these threads are a dime a dozen, but I just had to get my thoughts out in writing, and I thought I might as well share.
Currently we have a lot of spheres that could be very useful in magic, and we also have a very robust language system. Today at work I thought "Why not combine the two", and my brain started churning.
This would probably be suited to a high magic system. Each word would be learned seperately. Wizards would guard their words jealously.
Verbs: These determine the ultimate effect of a spell. In fact, the most basic spells are just verbs by themselves. This doesn't always work so well, because of the Rule of Refinement (below), but if enough power is put into it, a single verb spell can be very devastating. Or silly. Power Word Butter.
Adverbs: These flavor and/or empower the effects of a spell. They can be associated with a sphere, and if they match well with the verb, the effects may be magnified ("brightly incinerate" instead of just "incinerate"). Or if the verb has no sphere, the sphere may change the effect entirely ("Darkly teleport" moving the target through shadows, "teleport" just moving them) Currently as far as I know, there are no adverbs in the language files. Some adverbs would lend more power to a spell ("greatly" versus "slightly"), and thus be rarer to find. They'd also be guarded more carefully.
Nouns/Adjectives: Nouns and adjectives would determine the target of a spell. If there are no nouns, the spell tries to affect everything around it in a range determined by the power behind it. So for instance, to cast a simple firebolt at a creature to the south, you might use "ballistically burn south creature". Of course, this could target any creature to the south at all, and if there were more than one it might be wiser to use "ballistically burn south enemy".
Nouns have spheres as well. Nouns/adjectives that match with the verbs and adverbs in a spell mesh better, and generally allow for a more powerful effect. That said, while a dragon is associated with fire quite powerfully, using fire magic against it would be rather ill-advised unless you were trying to boost its strength or something.
Creatures and certain special objects may also have Truenames - proper nouns that affect the creature directly if used in a spell. Typically for sentient beings they're only created so that any random mage can't do it later on in the person's life. Creatures with truenames are also associated with whatever sphere(s) the name implies, and to a limited extent may take on some of their characteristics. A person truenamed "Sunblood" would be courageous, while "Hatesneeze" might get sick more often and be bitter. It's easier to Truename a creature or object predictably while it's young. Truenaming an adult can lead to some amusing consequences.
Now, on to the rules that give it a bit of regularity:
Rule of Refinement
A spell will affect any and every possible target that its words and power allows. That means that the previous example of "Butter" would attempt to coat everything in a sphere with butter. But the spell "Butter Feet" would look for and butter any feet, including table feet, orc feet, and hoary marmot feet.
Rule of Verbosity
The more words you use in a spell, the weaker it becomes. The exception is adverbs that amplify power, but even these can take from a spell's power if used excessively.
Rule of Will
A caster's will is linked to a spell, as is the target's if it has any. A spell may be resisted at the time of casting if the target is aware the caster is using magic. If multiple targets are involved, their will combined is greater than it would be for cancelling the spell, but taken on an individual level their ability to resist the spell is weakened. Once a spell is cast successfully, and the effects become physical, it may no longer be resisted except through normal means.
Casting time:
This is a big limitation for wizards on the battlefield. Obviously longer spells take longer to physically speak, but in addition, raising enough power to make it worth something may require chanting the spell multiple times, and releasing at the end. It depends on the wizard's power. Large rituals that destroy huge tracts of land in one big explosion are possible, but it may take months of chanting to gather enough energy.
The Ritual Chamber:
The most powerful spells in this case are the simplest. If you can manage to make it affect only one thing, that is. Truenames are useful in such cases, but sometimes you don't have one. In that case, getting a place that's isolated from other possible targets may be the best solution. But such things are not without their potential pitfalls. Making a chimera with "combine other creatures" could prove disastrous if the wizard's pet cat walked in at the wrong moment with a dead squirrel.
Enchanting:
Artifacts right now have names, and fit in well with the Truenaming thing. These could be whispered into the ear of the dwarf that makes them by powers unknown, and could be a source of new words for the adventuring wizard to discover. The names of artifacts could be spells on their own, their craftsmanship lending them their constant inexplicable power. This could become quite dangerous - "Whisperkill the Throne of Clean Death" slaying whomever sits in it when no one is looking. A suiting "gift" to an elven diplomat.
*pantpant* Ok, that's about it for now. I just like the idea of using something like the name creation screen to make spells in adventure mode. That and Gods using the same system to make really powerful/strange effects. "Sense Naughty Mortal", hehe.