Let us explain how you get 21 keys built into it in DMZ mode so that you can enter the all-new playable areas. Now that mysterious Building 21 is live and well in the DMZ of Warzone 2.0, you can begin making your way around the challenging new areas. Building 21 is the first big new addition to DMZ Mode, giving players an entirely new area to loot. Season 1 Reloaded brings with it an all-new building for players to explore, and this may be just Warzone 2s deadliest DMZ location to date. There is a new, mysterious building that has appeared in Warzone 2s DMZ mode.

The Season 1 Update Reloaded has just dropped in Warzone 2, and the most exciting new addition for DMZ players is Building 21. Building 21 went live in the Warzone 2 DMZ Extraction Mode on December 19th, part of the midseason Season 01 Reloaded update, and is meant to be a limited-time zone. As such, to gain access to Building 21 in Warzone 2, players will have to learn to obtain the Building 21 DRC access card by exploring the town of Al Mazrah Map.
Keycards labeled DRC Building 21 Access Card are looted by chance from the Rare Orange Loot Chest, Public Supply Drop Events, and Supply Drops that you receive by performing the Site SAM contract, or by taking down a Helicopter Commander. The building 21 access card is obtained from supply drops from taking down Supply Planes and HELO Helicopter commanders using the SAM Sites (marked by a white missile icon on your map). The DMZ Build 21 access map or key can be found either in orange boxes scattered across the map or in Supply Drops.
Missions to Building 21 are greenlit for those with access cards in the DMZ. Engage with extreme caution in this research facility, as competing Operators and high-tier enemies will be weapons free. Successful exfil is critical.
— Infinity Ward (@InfinityWard) December 19, 2022
Once users reach the supply drops in Warzone 2, there is a strong possibility of the building 21 access card being within a supply drop. If you had been saving up additional keys to use at random locations, you may have to burn through them first before you can target a Building 21 key card. You might have to loot more than one Supply & Supply crate in order to find the Building 21 keycard since it does not appear in every single one.
For the time being, players are probably going to want to stockpile their DMZ Building 21 keys and pull them out. There are certainly other ways to locate the Building 21 keys as more players engage its DMZ modes, and Activision has been leaked with even more information. As explained in a patch note, Accessing a bio lab known as Building 21 takes players out of al-Mazrah into an ultra-dangerous new area of DMZ. No one is entirely sure what is going on inside Building 21, but having such a mysterious object to pursue through an extremely unpredictable mode such as Call of Duty’s DMZ is quite thrilling.