NOTE: This is a brain dump. I admit I don't have all the final details on this.
Yesterday I had an idea for a new magic system, so I found myself writing up some of the basics at around 3am.
The reason for the new mechanism is the way that I see the current world of magic: there is little room for specialization. Let's say you want to become a pyromancer, someone who really likes lighting stuff on fire. You don't want to beat around the bush learning non-fire spells for the first several levels... You want to jump right in! "You want to be a pyromancer? Excellent! First you have to master ray of frost first!" ... Why would I want to do that?!? I want to light stuff on fire!!!
Furthermore, let's assume you do become a pyromancer of sorts. Over time your skill improves, but right now it's only shown in a handful of spells that involve fire and the only thing that increases in those spell is the number of dice you roll for damage. At high levels you should be able to control fire in any way you please, yet you are still bound by the spell list someone else defined for you.
So here's what I envisioned: let's say you want to be a true pyromancer. At 1st level, you immediately gain a modest fire attack that does 1d6 fire damage at range. As you gain levels or through alternate methods, you gain "spell points" (or "SP" for short) that allow you to enhance this basic attack or get other abilities. You can increase its intensity, turn it in to a burst attack, make it light things on fire, attack multiple targets, etc... etc...
So, for example, here's the basic options you can improve your basic attack with:
Effect: You gain a fire attack. The attack has a range of 50' and deals 1d6 fire damage for every intensity level when it hits. When you first choose this discipline you must choose whether the attack is a ranged touch attack or requires a Reflex save (DC 10 + Int modifier + 1/2 intensity)
Enhancement (Max 10): You increase the intensity of the fire attack by 1, up to a maximum of 10d6 damage.
Requirement: Fire Scholar 4
Effect: You can turn your fire attack into an area of effect attack. You can choose to reduce the attack's intensity by 1 to instead attack every creature within a 10' radius. A Reflex save (DC 10 + Int modifier + 1/2 intensity) negates the damage.
Enhancement (Max 5): For each enhancement level you can further increase the area of effect by another 10' and decrease the intensity of the attack by 1, up to a maximum of a 50' radius at the cost of 5 intensity levels.
Enhanced Fire Burst
Requirement: Fire Burst 3
Effect: Once per day, when you make a fire burst attack you can choose to have the attack deal half damage on a successful Reflex save (DC 10 + Int modifier + 1/2 intensity).
Enhancement (Maximum 5): For each enhancement level you gain one additional use of the enhanced fire burst attack per day.
Requirement: Fire Scholar 2
Effect: You can choose to reduce your fire attack's intensity by 1 in order to set the target on fire. On a successful hit the target gains the "burning" condition and takes an additional 1d6 fire damage at the start of each turn. The burning effect does not stack; if used on a target that is already burning it has no additional effect.
Requirement: Any Elemental Scholar 6
Effect: You can make your elemental attack against an additional target, distributing the intensity between them. Before making an attack, choose two targets and distirbute the total intensity level between them. The damage does not need to be distributed evenly.
Enhancement (Maximum 5): For each enhancement level you can attack one additional target, distributing the base attack's total intensity amongst all targets.
Long Range Casting
Requirement: Any Elemental Scholar 4
Effect: You can choose to reduce your elemental attack's intensity by 2 to double the range of the attack.
Requirement: Any Elemental Scholar 3
Effect: Once per hour, you can choose to reduce your elemental attack's intensity by 2 to increase either the attack roll or the save DC of the attack by 2.
Enhancement (Maximum 5): Fr each enhancement level you gain one additional use of precision casting every hour.
Each of these options will cost a certain amount of SPs.
Note something in the above: I don't specify what the fire attack actually is. It could be a bolt of fire, or it could be spontaneously generating a fire on the target, or it could be calling in to existence a large, flaming trout that slaps the target across the face. It doesn't matter what it is... mechanically, it all works the same.
This allows the player to describe how their fire ability manifests itself. So let's say you have an Intensity 3 Fire Burst 2 attack (3d6 fire damage to all targets within 20', 10 SP cost)... that's effectively the fireball spell. Or a flame strike. Or a really big flaming trout. How it looks visually is irrelevant and now up to the player's own creativity.
This also has an added benefit: the "spell points" reflect training, but leveling up need not be the only source of them. Let's say you find a really good arcane text in a dungeon, something that teaches you additional secrets on how to be an elemental caster. Studying that book at length can grant you 2 SPs, which you can immediately spend to improve your skill.
Also, the above allows you to either specialize as a "fire only" caster or make a highly diversified caster. At level 20 you can either be dealing a 10d6 fire attack (as an at-will, mind you) or you can spread out your SPs in pyromancy (fire), cryomancy (cold/water), storm mage (electricity/thunder), and others. Other disciplines could be necromancy or even straight up physical damage where your basic attack could be anything from magic missile to disintegrate.
I've been considering tying the above to a mana mechanism as well to limit the frequency that it can be cast. Like I said above, having a 10d6 fire attack that's an at-will could be pretty nasty... but is that really an issue? At 20th level a wizard is literally an arcane turret of destruction that could probably cast half a dozen 10d6 fireballs (maximized, even) on a whim.
I still need to figure out how to work in the non-escalating, non-damaging spells (things like charm person, sleep, etc.) or support spells (mage armor, shield, etc.) in to the above. I'm also considering upping the SP counts and gain per level so that a wizard can diversify more. For example, if they gain 4 SPs a level they can choose to gain 4 brand new weak spells or pile them all in to one discipline to really beef it up.
All this is in the works, rolling around in my head as I work on other projects. Maybe I'll write it up officially some day...