From the old BuildMagic pages on SourceForge...
"Moved to JBoss project. BuildMagic is a set of Ant tasks which make it easier to manage a development project between many developers. It sports extra support which the Ant folks have left out and provides other improvments."
You can get hold of it by checking out the buildmagic module from JBoss' CVS repository.
Buildmagic allows us to build all the modules at once or just a few as you develop.
I believe there is some documentation on the developers side of the site. Check the blue navigation under guides.