There is a master of magic multiplayer (and singleplayer...) java version now.

Well it has been there for quite some time but I just stumbled upon it. 

One of the best games ever made, check it out.

On second thought and playtesting: Don't. It's utter crap, nothing is working and I think they gave up on it. Try "Worlds of Magic" instead. I only have five hours into that but it's at least a decent remake.

Worlds of Magic on Steam