Call of Duty: How to Get the Rai K-84 in Firebase Z The highly-anticipated Firebase Z Zombies map has finally arrived on Call of Duty: Black Ops Cold War, giving players the chance to head to Vietnam as they continue the Dark Aether storyline. In addition to introducing new story elements and unique zombies, Firebase Z also brings a brand new weapon into the fold that players are desperate to get their hands on. It's called the Rai K-84, and it's an absolute zombie-killing machine. There are two ways to get your paws on one of these guns, one of which requires a lot of luck and the other is pretty time consuming.