Breaking Magic Circles

[Aubri]

I know this has been discussed before, so I'm hoping for quick answer.

If someone is in the middle of casting a thaumaturgy spell, and you throw a mundane object through the space above their magic cirle, does that break the circle? (Assume in this case that the circle is not being used to contain anything other than magical energy.)

[UmbraLux]

In narrative terms, you can usually break a circle (note: not a ward or block) by either crossing it with the same  material the circle is made from or by breaking the continuous line. 

Mechanically, you're maneuvering to negate the 'circle' aspect and probably need to beat the caster's skill.

[Aubri]

Well -- narratively -- in Turn Coat, Binder was threatening to break Dresden's ward with a thrown pebble (or Murphy's bullet). Do thaumaturgical circles follow the same rules, or can they be assumed to be "flat" and can only be disrupted by something breaking the plane of the circle? In this case, the circle is a solid piece, like the one in Harry's lab, and the interfering object is a pipe bomb. The circle's going bye-bye in a few seconds anyway... but I need to know if the thrower is going to have a chance to run from the fallout or not.

However, in game terms, I certainly wouldn't make it a contest against the caster's skill. The fragility of the thaumaturgical setup before the spell is fully cast is the big weakness of thaumaturgy in general. I was thinking of a flat difficulty of 3 to disrupt the construct, like a maneuver. Now, if someone were actively trying to prevent the circle from being broken, that would be a block...

[Mr. Death]

In narrative terms, you can usually break a circle (note: not a ward or block) by either crossing it with the same  material the circle is made from or by breaking the continuous line. 

Nope. The same material is stuff that won't break the circle. It's gotta be something foreign to the circle.

[UmbraLux]

Nope. The same material is stuff that won't break the circle. It's gotta be something foreign to the circle.

Leaves and sticks were used to cover a circle drawn in the dirt when summoning Toot.  Of course other items broke circles in other situations - a film canister at one point - so the intent may well matter as much as anything else.

Perhaps most importantly, the physical circle is still there until something erases part of it or changes its shape.  And, to change the shape, you need to be working in the same substance.  The mage himself can also break it - which makes sense since it's held in his mind at some level.  This is where opposed maneuvers come in.

Well -- narratively -- in Turn Coat, Binder was threatening to break Dresden's ward with a thrown pebble (or Murphy's bullet). Do thaumaturgical circles follow the same rules, or can they be assumed to be "flat" and can only be disrupted by something breaking the plane of the circle? In this case, the circle is a solid piece, like the one in Harry's lab, and the interfering object is a pipe bomb. The circle's going bye-bye in a few seconds anyway... but I need to know if the thrower is going to have a chance to run from the fallout or not.

Is the circle active or just scenery?  If it's active, is it being used as an aspect for power, a block, or a ward?

However, in game terms, I certainly wouldn't make it a contest against the caster's skill. The fragility of the thaumaturgical setup before the spell is fully cast is the big weakness of thaumaturgy in general. I was thinking of a flat difficulty of 3 to disrupt the construct, like a maneuver. Now, if someone were actively trying to prevent the circle from being broken, that would be a block...

If I remember correctly, maneuvering to take down an aspect is usually resisted by whomever put the aspect up.  (Didn't look it up to confirm - I could be wrong.)  If it's in active use, I'd at least have the target be the declaration roll's shifts and I'd probably allow active resistance - i.e. an opposing roll.

If the circle is being used as a block or ward I'd use the relevant rules.