It works, or well the one I have does. It makes Diablo appear as a normal creature in the blood moor, thus he can be champion, regular, ghostly, unique, etc. There are many of him too. I average about 10 of him per game. The reason he is available this way, to my understanding, is that Bliz did not enable him for the beta. However, by altering 2 files and adding an extension to your Diablo II shortcut, he appears.