A perfect place to store many of your dragons at once.
Introduced in Update 3.7, the Dragon Vault is a building that can be used to store Dragons in order to free up Habitat space. Dragons stored inside the vault become semi-inactive and will not generate Gold nor be able to participate in any other feature of the game. However, they will still count when calculating the strength of opposing Dragons, when applicable, in any battle venue. Additionally, friends of the player will still be able to hire the stored Dragon.
This building is unlocked at Level 10, has a size of 6x6 squares, costs 25,000,000 Gold, it is built instantly and yields no experience upon completion. Once the Dragon Vault is purchased, it can not be sold but, as long as there are no Dragons inside it, this building can be stored inside the Inventory by selecting the vault and then the button.
Storing Dragons inside the vault is done by selecting the building and then the option. From here, selecting any free slot by pressing the button will bring up the snapshots of all the housed Dragons the player currently has and then selecting any of the snapshots will automatically store that Dragon. The player can filter the selection of Dragons by a particular Element or by All. Dragons that are currently busy, such as those that are breeding, exploring ruins, having their Elements awoken, skill-training in the Dragon Academy or undergoing a process in the Fountain of Youth, can not be stored until they are free. Additionally, Boss Dragons are prohibited from being stored inside the Dragon Vault.
Storing Dragons can also be done by selecting a Dragon in their Habitat, opening their Codex Entry and then pressing the button which will automatically assign the Dragon to the first free slot in the Dragon Vault. This last button does not appear for Dragons under Level 4, even though Dragons of all levels can be stored inside the vault. Rehousing Dragons from the vault can be done by accessing the building and then pressing the button and then finally choosing a free Habitat spot.
The Dragon Vault can have up to one hundred slots. The first slot of the Dragon Vault is offered for free while subsequent slots have to be bought in exchange for Gold. The next nine slots cost 5,000, 10,000, 50,000, 100,000, 500,000, 1,000,000, 5,000,000, 10,000,000 and 50,000,000, respectively. After purchasing the tenth slot, each subsequent slot will have a price of 100,000,000 . The total amount of purchasing all slots is 9,066,665,000 Gold.