Call of Duty: Modern Warfare 3 has added a whole host of new features across several modes, including a new act for the Zombies mode. Act 4: Contact is the shortest act of the Zombies mode, but can provide a formidable challenge for endgame players.
All Act 4 Missions in MW3 Zombies
There are only two missions that makes up Act 4 of the Zombies mode. Unlike the other acts that require completing the previous ones to access, anyone can immediately start Act 4 regardless of progress through the launch campaign.
The first under Tier 1 is called Bad Signal and was added during Season 1. The final Story Mission of Act 4 is called Countermeasures and was added during Season 2. Both require players to investigate an Anomaly on the map, enter the Dark Aether Rift, and then escape it.
The Bad Signal mission offers the So Many Teeth Charm and an additional 10,000 XP for completion, while Countermeasures gives the Monkey Business Charm and 10,000 XP. Completing each mission opens a Dark Aether Rift, a teleporter to an endgame area located on the north and south sides of the Tier 3 red zone.
Players will need to get four key items that must be placed on the four pedestals located at the base of each Dark Aether Rift tornado. The Bad Signal mission gives one for the southern rift for completing it, while the other three, Dog Collar, Pill Bottle, and Surveillance Camera, will require their own specific methods to get.
The same goes for Countermeasures, and the northern Dark Aether Rift will require four separate items to unlock it. None are inherently difficult for endgame players, but will require a lot of traveling around the map.
For more help with Call of Duty: Modern Warfare 3 Zombies, check out our guide on how to use the Locked Diary after receiving it in the Bad Signal mission.