As Kaivax stated in a post a few moments ago, the PTR 3.4.0 of Wrath of the Lich King Classic opened recently, preparing for the arrival of the extension on September 27. This will feature content that will be available before the expansion over the next few weeks.
Currently, this does not yet contain the content in question, which the developers will activate in the coming days. The PTR will then go through the different stages planned, with the tests of world events, temporary dungeon bosses, Death Knights and other novelties.
Update 10/08 01:30: Start of the Zombie Plague event this Wednesday at 19:00.
