Diablo 3 wiki has 4 maps of routes to the spawn, can it spawn in any layout though? I'm restarting a lot more than i should be because i don't get the right layouts. http://diablo.wikia.com/wiki/Black_Mushroom
http://blackacrebrewing.com/hey.swf DotA 2 random player
From my understanding, it can spawn in any layout. But only in the same type of rooms as the images show. I wish you lots of luck in finding it as I'm hunting for the same thing and I spent nearly two hours (which isn't that long of a time) with no luck.