The Magic Crystal of Communication is a crystal that allows communication in the Nameless Zone. The Enchanter Kings received a message from Shirob using this, pleading for a rescue from the Land Beyond. The message, however, was very faint, suggesting the communication takes a certain amount of magical power and strength to convey a message in this way. Either way, there has only been one known to exist, so it isn't certain how Shirob actually contacted his fellow Kings.