Unless they did the exact same thing.

Besides, Harry really doesn't have the right temperament to make a good wizard. He's too straightforward and direct and it shows in pretty much everything he does.

Just look at the difference between how he shields and how McCoy shields. Dresden fights force with force, although now he tends to say deflect bullets instead of stopping them cold. McCoy has enchanted his robes to absorb the kinetic energy of any bullets that hit them (see Changes). What is the end result of these two approaches? It costs Dresden energy to stop bullets from hitting him, it gives McCoy energy when bullets strike him.

Dresden rarely "cheats", and it hurts him significantly as a wizard. It's honestly perhaps his biggest weakness. He's been getting better at it and he is young but he is still too direct.

The idea of using dozens (or hundreds) of prefatory rituals just to be able to use a greater ritual in the end? Does that sound like something Dresden would really do to you? Not that he can't do it, just that it would never occur to him to do it.

Yes, but players certainly will try this stuff.

Cracking discussion guys! I find that when there is no real risk, players can potentially create stupendously powerful spells and they have begun to get wise to this. Some good solutions to this. I may start all attempts to create an aspect at Mediocre, and increase the difficulty by 1 for each additional one created representing the casters fatigue.  Or use Sanctaphrax's +2 Difficulty per repeated use to encourage originality. Also how do you judge how long all this takes to prepare? The rules are a little wooly on this.

So to make things clear, this is how you could handle thaumaturgy:

1. Take a number of create advantage actions. This represents the preparation of your ritual; as a rough guide, each action takes a scene (30 minutes) but could be longer depending on the skill used. You must have at least one symbolic link to your target, and for true ritual magic, items representing the five senses, elements and the heart and mind. For a short cut, you can inflict or take consequences; a mild consequence is worth one invoke, a moderate is worth 2 invokes, a serious is worth 3 invokes and an extreme consequence is worth 4 invokes (a human sacrifice would provide 10 invokes). Depending on the situation, the Gm may not need to actually have the player's roll all of these actions; he would just assign a number of invokes the player has, based on the time they are spending in preparation; around 1 invoke per hour, per player.

2. Depending on the nature of the spell, use Lore to make an attack, overcome action or create an advantage action, which can be in the form of a challenge, contest or conflict. When creating an aspect, such as a ward or veil, if there really isnt any drama or need to make a roll, just assume the aspect is created. Any aspects created are resisted by your Will.

In a way then, thaumaturgy acts as a kind of uber evocation. I would add the following effects:

Duration: Normally thaumaturgy lasts until the next sunrise. For each invoke used from preparing the spell, you can extend the spell's duration by one step: a day, a week, a month, a season, a year, a decade, a century, a millennium etc.

Range: So long as you have a symbolic link to a target, you can use your magic at great distances. This applies to divination, summoning and transformation/disruption magic; you couldnt create a ward on a building across a city, for example. The Gm may apply penalties for long distance transformation/disruption spells; maybe -1 per 100 miles.

Barrier Strength: Normally if a veil, ward or containment circle is attacked or being resisted, you defend with your Will. For wards you may also add the threshold of the protected area. Rather than using an invoke for a temporary +2 bonus or reroll, you may increases the barrier's strength by 1 for each invoke used. For wards, the Gm can limit this to the ley line strength of the area; Edinburgh, for example, probably has a ward strength of around 50, owing to the ley line nexus. Other locations will probably have far fewer; the gm can effectively set a limit for his campaign, to stop players amassing unbreakable wards for their homes.

Extras: Sometimes you want to create spells with a special effect; maybe a veil that allows one way sight or only works against vampires, or a ward that has a wardflame. Each extra should cost one or more invokes depending on the strength of the extra.

Area: Spells tend to have a larger area than evocation magic; Veils cover a car-size area, Wards are attached to a building, containment circles cover an area you mark out using chalk and attack-type spells affect one target. If it makes sense to the spell, you can use an invoke to increase the spell's area to cover an entire zone, plus one additional zone per invoke used.

For example, a number of white council wizards need to create a veil big enough to cover an entire conference centre, requiring an additional 10 invokes. If time was of the essence, the Gm could play this out for drama. Since this isnt the case, the Gm determines that since the wizards only have a couple of hours, they put up the veil with a ward strength equal to their highest Will (+6).

Water: Water hampers the effects of magic. Any long distance magic will simply fizzle out when passing over a large body of water. Rain will also hamper a spell caster, applying a penalty to all rolls; a light shower may be -1 or -2, heavy rain could be -3 or -4, and a torrential downpour could be -5 or worse (maybe roll four fate dice to determine the weather condition- any penalty denotes the amount of rain- of course thats more appropriate for weather in britain...). A Gm could also apply a penalty if casting a spell near a large body of water.

Enchanted Items
If you have the Thaumaturgy extra, you may create magical items. In game terms these are bought as Stunts. If any rote spells benefit from bonuses gained from items, you can only use those rote spells with the item.

Sample items:

Blasting Rod
Any magical attacks made using fire gain a Weapon rating of 2.

Shield Bracelet
You may defend against physical attacks using your Will.

Enchanted Leather Duster
This leather coat has an Armour rating of 2.

Warden Sword
This sword has a Weapon rating of 3. For 1 Fate Point, you may either counter an enchantment with a Fantastic (+6) skill result, as long as your blade strike the target, or the weapon is treated as a Weapon 6 for one attack.

Harry's Staff
You gain +1 to all Focus rolls when using fire-based evocations.

So regarding thaumaturgy, maybe something like this:

Thaumaturgy
Permissions: You must have an appropriate aspect related to your magical training.
Cost: 1 Refresh

Normally, you can use all forms of thaumaturgy, but you may choose to be a focused practitioner, focusing on one form of thaumaturgy or one thematic type, such as necromancy. You do, however, gain +1 to all rolls involving your specialism. 

Thaumaturgy is the magic of symbolic links; you cast a spell on a small scale, invest it with energy, and use symbolic links to expand the power and scope of the spell. For very powerful spells you will need top fuel the spell with greater magic by tapping into storms, leylines, emotional energy, pain or even blood sacrifice.

Preparation
You need to build a construct to hold the energy in your spell. Create as many aspects as you feel is necessary as preparation for this; it usually take one scene for each create an advantage action and will require Average (+1) skill results but the Gm may assign higher values when he wants more drama and tension. Once the preparation is complete, you must make a Lore roll to build the construct; this typically takes a scene and your result determines the spells complexity. If you are desperate, you may inflict or take consequences; each consequence increases the spells complexity by the consequence's value.

Powering the Ritual
Now you need to gather power into the spell construct. Make a Focus roll with a difficulty equal to the complexity of the spell. For each additional exchange spent gathering power, you may add 1 to your skill result.

• If you fail, the ritual fails and all the preparation is wasted; perhaps you are distracted while casting. You may choose to succeed, but you must take fallout or backlash just like an evocation spell.
• If you tie, you ritual is ready to be cast, but you must take a point of mental stress. If you cant do this, the spell fails and the preparation is wasted.
• If you succeed, you channel the energy into the spell.
• If you succeed with style, you channel the energy into the spell and gain a free boost; you may use this to increase the complexity of the spell by 2.

If the spell construct isdamaged or your concentration is broken in any way before releasing the spell, the spell fails and you must take fallout or backlash.

Releasing the Spell
Decide what you are going to do with the spell:

Solve an improbable or impossible problem: Take an overcome action using the spell's complexity. The Gm sets the difficulty; for example, tracking someone with magic might require a Legendary (+8) result.

Creating Lasting changes in people and things: Take an attack action using the spell's complexity. Depending on the effect this will either be resisted by Physique or Will, and cause physical or mental stress. Any consequences inflicted result in lasting transformations.

Provide Inaccessable knowledge: Create an aspect using the spell's complexity. Characters may defend using Will.

Allow interaction with the supernatural: Take an overcome action using the spell's complexity. The supernatural entity can resist your attempts with Will.

Shape magical energies into a physical form: Create an aspect using the spell's complexity. This is typically Average (+1), but higher difficulties may be needed for complicated veils, wards or conjured items; a veil that is a one-way mirror may need a Good (+3) skill result, while conjuring a field of animated frogs might require a Legendary (+8) result or more. Any aspect created provides a passive opposition of Mediocre (+0), and you may actively defend using your Will. If you gain a success with style you gain an additional free invoke for every 2 shifts of success above 3[size=78%] [/size]

Duration: A standard spell has a duration of "till the next sunrise" unless the spell is an attack or overcome action. You may reduce your shifts of success; each shift reduced increases a spells duration by one time increment:
a day, a few days, a week, a few weeks, a month, a few months, a season, half a year, a year, a few years, a decade, a generation, a mortals lifetime, several lifetimes etc

For instance, Harry needs to summon Chauncy the demon. He first needs to build a summoning circle to contain him. He reckons 11 complexity should be enough to resist Chauncy escaping for the duration. He makes a Lore roll to research demonology, Resources to create a new silver summoning circle, Scholar for more research and Will to meditate before the ritual. He makes all of these rolls, so makes a Lore roll at +8 to build his construct, getting a result of 10. He decides to take a consequence from a migraine, boosting the complexity to 12. Harry is now ready to power the spell and decides to spend 10 exchanges casting the ritual so he needs to make a Focus roll at +9. Fortunately he makes that and can finally release the spell. The Creating the Summoning Circle aspect will require an Average (+1) result. Thats 11 shifts of success, providing 3 invokes and a passive opposition of 11. Before summoning Chauncy, Harry goes for a lie down...

When doing a full Fate Core conversion, I wouldn't bother with elements any more. That's a thing for aspects now.

So do mean something like Master of Fire, Spirit and Air? Wouldn't that be more useful than a focused practitioner with just Master of Water?

You are mentioning focus items a few times, yet you don't say what they are actually supposed to do. I wouldn't really bother with them, to be honest. Maybe make them a weapon instead, so when you are shooting magic with a focus item, it is similar to a gun. Or a focus item can be a stunt, for example a permanent justification to roll will for physical defense with a shield bracelet. Like your reactive shield, only without rolling to put an aspect up. The stunt pretty much is the aspect.

I was going to keep it pretty much as dfrpg - each provides a bonus to Will or Focus with a certain element. But I can see a stunt may be easier.

Thaumaturgy, to me, is very off the way you describe it. Since it isn't really a skill so much as a series of actions (not in the "the four actions sense, but a "first you do this, then that and so forth") you take, it can be a lot of different things, depending on what you want to do with it. It can be a simple overcome action, a contest, a challenge, or it may even become a full scene with a conflict and everything.

You want to open a lock? That's an overcome action.
You want to do a tracking spell? That's a chase, just with magic against athletics instead of athletics against athletics.
And so forth.

The ward you describe, to me, seems pretty boring. If the ward is never used, there is no need for it to even exist. If the ward is used, then someone is trying to get into your house, it is interesting, it is exciting, play it out. There is a "security specialist" stunt for burglary, that lets you get into active opposition if someone is trying to overcome a security system you installed. Why not do the same thing here? Just have an aspect like "this place is warded", and when someone is trying to get through, you make it a conflict wizard against intruder on the basis that so long as the wizard wins, the ward holds up.

And before you get into casting the spell and playing out what you do, you can prepare, create advantages that you might need. Some might even be required to just be able to do the spell. Like a symbolic link.

Very interesting ideas. I think I would need to work through several examples to know how to do stuff.

Extra: Evocation
Permission: An aspect reflecting your magical training such as White Council Wizard or Focused Practitioner.
Cost: 1-2 Refresh

You may use Will or Focus to achieve magical effects. For 1 refresh cost you are a focused practitioner and are only able to use one element. For 2 refresh cost, you are able to use any 3 elements.

Overcome: Use Will to solve a problem with magic using brute force, such as blowing down a wall or jumping over a pit. Use Focus to solve a problem with magic using finesse and fine control, such as picking a lock or lighting a fuse. Counter a spell using Will, resisted by the Will of the caster.

Create an Advantage: Use Will to alter the scene or an individual with magic in an obvious manner, such as a wall of fire or quicksand. Use Focus to alter the scene or an individual with subtle magic such as a veil or changing the emotional mood. You suffer -1 for each zone of distance to your target.

Attack: Use Will to harm a target in a direct manner such as a fireball or force bolt. Use Focus to harm a target in a subtle way, such as removing air from their lungs. You suffer -1 for each zone of distance to your target.

Defend: Use Will to defend against a magical attack. Use Will to defend if you have an appropriate aspect in place.

Rote Spells: Choose a number of Rote spells equal to your Lore. If you attempt to cast any spell, other than a rote spell, you must take one mental stress. Each rote spell should have a name, preferably in a foreign  language.

Focus Items: You start with 2 focus item slots.

Stunts:

Sorcery Sharpshooter
When using magic at range, you may ignore the normal range penalties. You must still be able to see your target, however.

Arcane Refinement
Choose one element or type of thaumaturgy. You gain a +1 bonus to either Will, Lore or Focus actions, when casting magic of that type.

Reactive Shield
If you are attacked, you may make a Will roll to create a shield-based aspect on yourself, which you can instantly invoke if necessary.

Magical Thug
When making an attack with magic, if you take a point of mental stress your attack has a Weapon Rating of 2.

Magical Heavyweight
Requirement: Magical Thug.
Your magical attacks have a Weapon rating of 2. If you take a point of mental stress your attack has a Weapon Rating of 4.

Selective Targetting
When using magic, you may effect more than one target without having to split your result.

Smoke and Mirrors
When using spirit magic to create veils, you may take a point of mental stress to create a special effect such as a one way veil, a veil that only blocks against vampires, or a veil large enough to cover several targets without splitting your result

Magical Macgyver
If you have any focus item slots free at the start of a session, you may spend a fate point to assign them to a new item that you just happen to have on hand, or are able to create with a roll of duck tape and swiss army knife.

Arcane Arsenal
You start with an additional 2 Focus item slots

Natural Born Elementalist
You may use an additional 2 elements when using magic.

Walking Spellbook
You may choose an additional 2 rote spells

Dropping the M-bomb
When making a magical attack affecting an entire zone, you may take a point of mental stress to affect an adjacent zone.

Makes sense. Though I wonder, is that something that Fate Core still does, or is it dealing with things like that in another way?

Actually i think you may be right. Attacks and aspects can effect entire zones, but will effect you as well. I may go with a -1 penalty per zone of distance to the target. If you want to blitz a zone it will need to be at least one zone away. You can always split your results as well. Stunts is probably the way to go for selective zone-blasting magic