Earlier this week Gears fans figured out how to trigger Warzone--it has to be done from a private Team Deathmatch, while hitting the A and B buttons simultaneously in the match's parameters menu. Warzone's exclusion and mysterious reappearance led to rumors the mode was going to be included later as paid DLC, but an Epic Games multiplayer programmer told Eurogamer that was not the case.
via Kotaku http://feeds.gawker.com/~r/kotaku/full/~3/JA4nYVnLIqY/story01.htm