Chamber of Gnomes

The Chamber of Gnomes is a location in Plants vs. Zombies: Garden Warfare 2. It is technically speaking located in the Backyard Battleground, though it is found in the sewers underneath the said area. Accessing the Chamber of Gnomes unlocks the Gnome Man's Land achievement.

Accessing
To access the Chamber of Gnomes, the player must find and collect all 54 golden gnomes spread out throughout the game's maps. 14 of them are found in the Backyard Battleground and its subareas but there are also Gnomes hidden in actual gameplay maps, specifically, there are two per map.

Once all Gnomes have been collected, the player must answer a telephone located near the docks in Backyard Battleground. When the player answers it, a strange voice will tell the player that they have left a key for him/her and that they trust the player knows how to use it. A Gnome Bomb will then appear on the docks, which the player must pick up and deliver to the sewers and place next to an entrance located just opposite to the entrance to the Crazy Targets Range. Once placed, the Gnome Bomb will detonate, destroying the iron bars blocking the entryway, allowing the player to enter. The corridor that the Gnome Bomb opened will lead to the Chamber of Gnomes.

Layout
The Chamber of Gnomes is made up of four large rooms.

First Room:
The First room is a large circular antechamber with several piles of coins lining the walls. There is a large golden gnome located in the very center of the room with a chest located right in front of it. This chest requires 200 stars to be opened, making it the game's most expensive chest. All of the 54 Gold Gnomes that the player collects will be placed in this room when found. There multiple shelves next to the walls with slots for up to 9 gnomes each. Once the player fills up all shelve slots, the door located in the back wall of this room will open, revealing the next room.

Second Room:
The Second room is a small rectangular room with three chests in it. These chests are free and do not require any stars to be opened, and they contain both coins and Backyard items. This room contains a hidden switch located just above the entrance door, which, if shot, will open a secret door located just behind the the center chest. This door leads to the third room.

Third Room:
The Third Room is a long rectangular chamber with several Gold Gnome statues decorating the walls with coin piles next to them. This room contains a set of wheels located in the back wall. These wheels are a part of a lock mechanism that the player must unlock in order to access the next and final room. In the center of the room, there is a large control panel with three levers in it. This control panel manipulates the wheels and must be used to align the wheels correctly to open the door lock. If the right combination is entered, the door will automatically open, granting access to the final room.

Fourth Room:
The Fourth Room contains a singe large Gnome statue sitting on top of a throne with three chests in front of it. Two additional chests can be found on the edges of the platform. None of the chests in this room require stars and they can be opened freely. In the center of the room, there is a small podium containing what appears to be a record player with a small gnome on it. This room is the last one that can be accessed and does not contain any additional doors. Once the player enters this room, the Chamber of Gnomes is fully explored.

The first room is accessible as soon as the Chamber itself becomes available, the second cannot accessed until all 54 Gold Gnomes have been found (indicated by the Gnome shelves in the first room) while the third room can be accessed by shooting a hidden switch found in the second room. The fourth and final room can only be accessed by entering the right lock combination into a lever puzzle located in the third room. This room is the last one that can be accessed and once the player opens it, they will now have access to the entire chamber.

Loot
The Chamber of Gnomes contains multiple chests. All of them will yield coins when opened while some of them contain backyard items which the player can use to customize their Backyard Battleground. There are two customization items that can be found in the chamber, specifically, two hats. The first one can be found in a chest in the center of the first room which requires 200 stars to be opened. The second can be found in the fourth room, in the center-most chest.