I’ve seen 16th-Century woodcuts of wizards conjuring up demons, and the wizard stands inside a magic circle for protection. as the demon rises from the ground outside the circle. But in most modern magic-fantasy stories, the wizards stands outside the circle and the demon is imprisoned within it.
What’s the right way? I mean, it’s not something you wanna screw up.
I would think it would depend on why you’re summoning the demon. If you just want information, conjure it inside the circle to restrict its movements. If you want it to, say, smite one or more of your enemies, you stand in the circle and conjure the demon outside it. Wouldn’t make a lot of sense to conjure you up a smitin’ demon and stick it inside the circle.
The term for this is evocation–which is different from invocation. The magician stands inside the circle, which serves as protection, for all magical operations. For evocation of a spirit (any sort of spirit, demon or not), a triangular shape is prepared for it to manifest in just outside the circle. Invocation is all done inside the circle with no external manifestations.
And Anya and Willow’s performance should not be taken as an example–they got smashed up pretty good. Just goes to show you that a nice pentagram might have helped them out.
I seem to recall a line in The Tempest, something about “Weave a circle 'round me thrice”, but I can’t seem to find it. Perhaps another Doper knows the line I’m thinking of? In context, it might prove instructive here.