Specifically, physical actions on each side of the circle.
There are many ways to visualize the power limits of these Circles, but most germane to this discussion are the following:
a) a cylinder extending an arbitrary distance above the target, but with a floor at the level of the circle
b) a cylinder extending an arbitrary distance above the target, and a shorter but still arbitrary distance below the level of the circle
I think that's taking things a bit farther than the circles are described. As gamers we look for limits on things so we can exploit them, but in the books a circle is a circle.
Here's how I see it working (based on the sources cited above):
1) If you can't force your way out of the circle via your mystic power (the way the Erlking almost did) then you can't leave the circle.
2) Flying over the circle, tunneling under it, smashing the material the circle is drawn on - that's leaving the circle and you can't do it (see 1 above).
3) Why? Because it's magic.
Okay - I'll expand on point 3. The circle is a form of threshold, defining the world as "inside" and "outside". It's not a normal threshold like the type you find on a house, but works metaphysically like a threshold. When we try to define it further things start to breakdown and questions about burrowing, flying, etc matter, as does "is there plumping under the floor", "is the wiring in the ceiling breaking the circle", and a host of other issues. Keeping things at "It forms a barrier because it's magic" fits with the way it's shown in the books and the feel of magic in the DV.
Going back to the books:
Toot-toot was imprisoned in a circle that had grass, pebbles, twigs etc in it - but he couldn't pick up a handful of grass and toss it at the circle. Why? Because he couldn't break the circle.
Maybe if Harry ever does do that "what's a threshold? How is it made?" research we'll learn more, but I have a feeling that he'll be too busy to do it in the next book.
You need leverage to break Concrete like that with sheer pressure. You need something holding you down so that all of the force generated by your pushing is going into the concrete and not being absorbed by your own body. Strong the Erlking or a demon might be, but they've got to work with physics just like anything else.
Leverage amplifies force. Where you hold the sledgehammer determines how much of a mechanical advantage it gives you.
But if something is strong enough then doesn't need to amplify the force its strenght produces. Think pile driver coming down and breaking a section of sidewalk - that's how I see someone with Might +10 or higher being able to stamp his foot. When it comes to smashing things, Might +10 is just Great Might combined with Supernatural Strength - easily doable.
Richard
