I know, but the point is that it's not a universal issue among toolkits and the issue remains with games like Cortex and Fate. There may be lots of different ways to do magic, but where and how do you start? Especially when the game doesn't have much in terms of concrete examples. (Thankfully there is ToX out now.)
There are three ways that immediately sprang to my mind:
1. Tales of Xadia method:
Dedicate a Distinction in the following way: <adjective>+<magic vocation> (for example, Hot-headed Sun Mage).
Select one specialty (magic type) and assign a rating to it.
Assign a rating to an associated Asset (this allows you to select a number of spells).
When you cast a spell, use a dice pool of Distinction+Specialty+Asset.
The spell description informs you as to the nature of the effect in question, however it can be heavily modified by the result of the roll and other things.
Pretty complicated, but allows you a lot of flexibility, and your nonmagical stats do not overlap with magical ones preventing mages from becoming superior character choice.
2. Powers.
2.1 Pick or create powers in a prime set. Rename those that need to function as spells, and assign additional SFX (special effects) with costs.
Create an Elemental Earth Object spell (Elemental Control: Earth power) would by default create a temporary asset that lasts a scene for a price of 1 PP, with a rating based on your power rating. Adding more power or control or area would require use of an appropriate SFX with additional cost.
NOTE: (loosely paraphrasing the rules) A power must have at least one SFX (SFX is an activation condition and a benefit), and at least one limit (specific condition that shuts down the power, prevents its use or severely weakens it).
Example: Create an Elemental Earth Object spell: While standing barefoot on a ground, stone or any stable mineral, invoke an incantation to conjure a geometrical object composed of dirt or stone within 30 feet.
Benefit: The object immediately moves in accordance with laws of gravity. It is not attached to surface. Double effect dice if rock is selected and the object is falling from 20' or more.
Limit: Step down effect if blocked by solid barriers or liquids.
2.2 Allow to retrain Powers to rewrite them or add another SFX to gain more flexibility for XP.
3. Magic as Skills with Specialties.
3.1 Basically, for a Skill Lightning Magic, you can create specialties like Create a Storm and Call Down a Lightning Strike:
Lightning Magic Skill d8 (Create a Storm d6, Call Down a Lightning Strike d6).
You purchase all of these as three skills, the gain here is that while using Lightning Magic you gain d8 in your pool. But Creating a Storm will grant you d8+d6.
Later you may purchase additional SFX, step up dice or add more dice.
To balance it, add SFX with a Plot Point cost.
