So something like this, building upon all of your rules
Evocation
Permission:A high concept (or, with GM permission, other relevant aspect) indicating that you can work magic.
Cost: One refresh.
Limitations: Evocation should have some appropriate thematic limitations - perhaps you work with, say, just fire, force, and wind. Work this out individually; a spellcaster whose paradigm is the eastern elements of Wood and Metal would be very different from a hippy wannabe-druid or a retired ectomancer, even if the power is mechanically the same. Each player must choose 3 elements to be able to use. Typically a character will be able to use three elements.
Effects:
Overcome: You may counterspell an existing situational aspect created by magic, opposing your Will against the Will of the spell caster, for evocation magic, or the spells casting roll for thaumaturgy spells (see below)
Create an Advantage: You may create an advantage with magic, using Will, Fight, or Shoot - though Will is limited to personal range aspects, Fight is limited to the zone you're in, and Shoot is generally limited to offensive effects - though subject to GM discretion; a wall of fire might be acceptable, for example, as it's thematically pretty similar to using a gun for a "covering fire" type of aspect. As with ranged attacks, create an advantage takes a -1 penalty for each zone of range - again, this can be offset with appropriate focus items.
Attack: You may attack with magic using either Fight or Shoot skills, as appropriate. Working magic at range is difficult, though; you're at -1 for each zone your target is away from you - though this can be offset with appropriate enchanted items.
Defend: You may defend yourself from attacks using your Will skill - if and only if you have an appropriate aspect placed on the scene, such as "wall of fire", "dome of force", "entropic shield", or the like. (Note that this will usually apply only to physical combat... but only usually; for example, one could easily imagine a wall of fire justifying using Will to defend against an opponent's attempts to intimidate you.)
Enchanted items: You may create magical items, potions, weapons or items. You gain 2 Enchantment item slots which can be assigned as follows:
A focus item providing +1 bonus to a spellcasting action with an element/type, or +2 when using a specific spell (shield charm adding +1 to spirit defends, a blasting rod adding +1 to Fire attack rolls etc).
An item that has a Weapon rating of 1 for each slot assigned, when casting attack spells (blasting rod, staff)
An item with an Armour rating of 1 for each 2 slots assigned to it (a toughened duster)
An item permanently enchanted with a situational aspect, such as a penny farthing that has the Lightning speed aspect placed it on it. You gain 1 free invocation per session for each slot devoted to the item. Alternatively, each slot could be a potion- once drunk, the imbiber gains the aspect with one free invocation.
Some possible stunts:
Magic Utility Belt
You gain an additional 2 Enchantment slots
Magical Thug: For the cost of a point of mental stress, you can make a magical attack that counts as weapon rating two... or +1 weapon rating over whatever enchanted item you're using.
Reactive Shield: You've practiced to the point where you can raise a particular type of shield with a thought; you don't need an established aspect in order to defend yourself with Will. (But you do still need appropriate justification - a force shield is unlikely to protect you from much in the way of social or mental attacks, for example.)
Focus, Focus, Focus: As long as you have an appropriate focus item in hand, you may use Will instead of Shoot for ranged attacks or create an advantage actions using magic.
Burn It All Down: +1 to any attack or create an advantage action using fire magic... but if you fail by two or more, the GM gets to place a scene aspect as the poorly controlled spell sets something else on fire. And yes, the GM gets a free tag on that, too.
Thaumaturgy
Permission:A high concept (or, with GM permission, other relevant aspect) indicating that you can work magic.
Cost: One refresh.
Limitations: Thaumaturgy allows you to do pretty much anything. If you wish to play a focused practitioner, with only knowledge of a single type of thaumaturgy, or a narrow theme, you gain +1 with all uses of it.
Thaumaturgy is all about preparation and ritual. This is really a series of create advantage actions using appropriate skills (Lore to research or prepare the ritual, Scholar for mundane research, Resources to acquire ritual items, Contact and Rapport to seek help, Crafts to create ritual items, Burglary to acquire symbolic items, Survival to locate a good ritual site etc.). Once the preparations are complete (the physical construct) the spell must be cast. This requires a roll based on what you are trying to do; Rapport for Summoning, Will for Binding, Lore for Divination and Potions, Craft for Conjuring and Crafting Items, Deceit for Veils, Will for Wards, Provoke for Transformation and Disruption, Athletics for Transportation magic, Lore for Worldwalking. Obviously, this is likely to be high, especially for very powerful spells. If you are desperate, you may take consequences, adding the corresponding level to your total.
Casting Time: Thaumaturgy spells take a little more time than evocation spells. Time must be spent to harness the energies in the spell. Each round you may channel a number of invocation bonuses equal to twice your Will. If you want to rush things, each additional +2 bonus will cost you 1 point of mental stress.
Disruption: If someone manages to destroy alter or damage your physical construct, or attack you while you are casting, things can get very messy indeed, resulting in uncontrolled magic spilling into the world, with the degree of destruction based on the power of the spell- use the current bonus being applied from invocations etc as a guide. The caster is likely to take this as shifts of Physical or mental damage
For example, Harry is attempting to prepare a tracking spell to find a lost child. This will require a Lore against a Legendary (+8) opposition. Harry needs at least one symbolic link for the spell, so he asks her parents to look around her room, using Investigate to create the aspect *Samantha's Hair, with two invocations. He then uses his Lore to first prepare the ritual space, and creates a *Circle of Chalk in an alleyway near the house, gaining a free invocation. He makes a Lore roll, using all three invocations, so he gets a total of 10. Until sundown, he will be able to track her whereabouts. Its getting late so he hits the streets....
Victor Sells wants to create a heart-exploding spell. The unfortunate target will have to make a Physique roll against his Will roll or suffer physical stress for each shift that gets through. To cast the spell, Sells will need to make a very high total (over 30) to guarantee killing the target , so he needs some serious research to pull this off. He is desperate so will take an extreme consequence *Power Mad which he can add 8 to the roll. He also takes *Bargain with a Demon, a severe consequence for another +6, and a moderate consequence *Trapped by the Storm, for another +4. He then uses Lore to create a *Ritual Circle (+4), Scholar to be in the right place for *Eye of the Storm (+2), Provoke to place *Emotional Trauma on his wife and the Beckitts (+6). Finally, he uses Lore to ritually kill a rabbit with a spoon, using *Dead Rabbit to gain a further +2, and a further +2 from *Victims Blood, an aspect he created earlier. Thats a healthy +34 bonus to the Will roll.With a Will of +3, Victor can safely channel +6 of bonuses each round- it will take him 6 rounds to cast the spell, assuming no meddling wizards disrupt his spell...
Enchanted items: You may create magical items, potions, weapons or items. You gain 2 Enchantment item slots which can be assigned as follows:
A focus item providing +1 bonus to a spellcasting action with an element/type, or +2 when using a specific spell (shield charm adding +1 to spirit defends, a blasting rod adding +1 to Fire attack rolls etc).
An item with an Armour rating of 1 for each 2 slots assigned to it (a toughened duster)
An item permanently enchanted with a situational aspect, such as a penny farthing that has the Lightning speed aspect placed it on it. You gain 1 free invocation per session for each slot devoted to the item. Alternatively, each slot could be a potion- once drunk, the imbiber gains the aspect with one free invocation.