Jim Butcher on Magic Circles

[Richard_Chilton]

I've had a bit of time to go through the big list of everything Jim's said about the Dresden series (found at http://www.jimbutcheronline.com/bb/index.php/topic,21772.0.html - note: spoilers for the series and setting) and I found this one on magic circles:
http://www.jimbutcheronline.com/bb/index.php/topic,1942.msg37964.html#msg37964

It looked interesting so I thought I'd share how vulnerable a circle is when it isn't active.

Richard

[Raiden333]

Also, something I haven't seen mentioned anywhere in the rulebooks: It does not take any magical talent to make a magic circle if you're willing to prick your finger. In Dead Beat:

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Butters makes a circle by himself using chalk (and a drop of his own blood to seal it).

[Nyarlathotep5150]

    Also In Blood Rights:
      

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Kincaid creates a circle to ensure Dresden doesn't use magic on him. And While Kincaid isn't human, its been made pretty clear that he doesn't have any magical ability to speak of.

    In my games, I just rule that circles fall under the minor rituals trapping for lore. Anyone can do it if they know how.

    

[Drashna]

I think the general consensus is that a normal magic circle is a mundane/sponsored ritual.   I think it's the mechanic that works the best, and most reliably.

[Nyarlathotep5150]

   I just say it works like a threshold of a strength equal to the shifts accrued in the Lore Role. It can end up with some high ratings that way, but since it wont stop projectiles or swords, and can be broken by anyone with access to a stick, it evens out.

[Tbora]

Magic Circles are easy things that can be put together with a simple supplemental action, their is big advantage is that they block magic.

Period.

But they are so simple to break its not even funny.

[Belial666]

Actually, they don't block magic, period. If that were true, all Harry had to do to hide Morgan would be to put him into an activated circle and suddenly no magic could find him. Similarly, a simple circle would be enough to keep the Archive powerless - which is also definitely not true - or prevent the magic on MacFinn from turning him into the Loup-Garou.

The bigger the magic that needs to be stopped, the more elaborate and powerful the circle needs to be.

[Drashna]

Which is why you'd use it as a perpetual block.  Specifically, like a Threshold. In fact, the book recommends that is how you handle them.  well, rather... Bob suggests in in the side of the page. YS230.   Determine it's strength by the person creating it.  That or treat it like binding a spirit, plus maybe some difficulty.

As for McFinn, I'd say it doesn't block the "spell".  If anything it feeds off of him.  The circles are meant to contain him, not the magic.  So the complexity that it requires greatly ups the difficulty to create it and to escape from it.

[Nyarlathotep5150]

   It would do nothing to stop the Loup-Garou transformation. The spell lies dormant within Mcfin until the full moon rises, then it casts itself on him. The magical energy happens completely within his body, so the circle can't do anything about it (circles stop magic from crossing through them, they don't stop you from casting spells in them). Then, once he changed he'd be immune to magic and able to cross the circle with ease.
   The circle did stop the Archive from using magic, that was the whole point, but shes a completely physical being, so nothing was stopping her from just leaving the circle and casting a spell.
   It would have been useless to try to hide morgan in a magic circle, since Harry was well aware they would have come looking for him in Chicago anyway (plus the entire thing was a set up to keep them chasing Morgan).
   A circle is like a wall. It doesn't stop you from casting spells in it. It just stops magic from crossing the perimeter.

[hank the ancient]

Going off the books, harry says at one point that if you're going to do magic you will learn about circles. they're like addition is for math, even if you can't solve a quadratic equation they become standard for just being able to function.

[Peteman]

Technically, the circle prevented the Archive from harnessing more magic then what was in the circle. She simply was chucking around a lot of super-efficient spells.