Though the box isn't exactly as I described, I have identified it as _The Lords of Magick_, by David Marsh.  Has anyone seen it?

Scott Andrew Hutchins
http://members.home.net/scottandrewh

"It's a queer world, and the longer I live in it the queerer I find it.  Once I thought it would be a good idea to regulate things myself, and run the world as it ought to be run; but I gave it up long ago.  The world's a stage, they say; but the show ain't always amusing, by a long chalk, and sometimes I wish I didn't have a reserved seat."--John Merrick, _Aunt Jane's Nieces_, by L. Frank Baum

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