Drawing Circles

[Dracorex]

So....I was writing rote spells, agonising over constructing defensive spells, and then it occurred to me: how does one define a circle as seen in the books? The way they act as a barrier to all magical energies, and as a summoning tool?

A manoeuvre to place a temporary Aspect on the person or a block? Neither, but rather a straight skill roll to make the circle, then narratively handled? I suppose the first to provide a tag/invoke for aiding your summoning, and the last for blocking magic. I'd like to hear your thoughts, though.

[Haru]

Short answer: Yes.

Long answer: All of the above. It really depends on what you want to do in that particular situation. A maneuver + tag for effect would be the most common though, to keep magical energies and/or entities out.
For summoning or any ritual magic, I think I would require a circle as a baseline, and if it is a particularly elaborate circle, it will have additional aspects that can be tagged, but the circle itself is simply what the spell requires (as covered by the "up to your lore skill without preparation" thaumaturgy rule).

You could also throw up the circle as a block against magic using conviction. Most times, it will be weaker than just have it as a maneuver + tag for effect, but it all depends on what you are doing. For example in a summoning, you could have the circle justify a duel of the minds, where the wizard is holding the demon in place and the demon is struggling against the wizard. A simple tag for effect would be boring here.

[blackstaff67]

For Thaumaturgy, I'd have to say that a Circle is a maneuver + tag effect.
For blocking magic itself, it seems to be an near absolute in the books, given that Binder was so thoroughly slapped by Molly's circle in Turncoat.  Keep in mind that the circle Molly drew (in gravel, in a hurry) probably was not the perfect circle we'd associate with it such a circle but was still effective.  It's still a ritual that relatively fast and that anyone can perform--ask Mr. Butters. 
Perhaps plot-device capable entities (Uriel, perhaps, or other such being) may laugh at a circle, especially if they are outside it.
For summoning magic, I'd have to say the longer you take to make the circle (see trading shifts for time scale), the better the tag such as when Harry summoned/trapped Mr. Erlking.  OR
note that number of items Harry placed in the Circle, each item perhaps being a tag.  Given the power of the Being he was attempting to summon and keep there, he'd have needed them.

Note that Harry has a Circle in his basement that he can tag, plus another tag for the copper (Resources,maybe?  Deceit or Burglary for my own sorceror) and tag for the little sigils in the ring (certainly another tag, perhaps Resources another Contacts).