Defend the Vault is an event in Diablo Immortal. It is exclusive to Immortals players, and is their counterpart event to Raid the Vault.
Gameplay
Immortals may sign up at the entrance in the Hall of Ascension to join the queue to defend. When a Shadow party raiding the Vault triggers an alarm (either by entering the 4th floor or failing to kill a Warden in time) the first Immortal party in the queue gets the chance to defend. However it may be possible for parties to get skipped depending on the power difference between the Shadow and Immortal parties. The Immortal party leader may also choose to automatically skip strong raids. When the alert comes up, the leader does not have to click on a button but all other party members must click accept. (This is an important distinction as for the party leader the "cancel" button is in the same place as "accept" for other party members, creating a chance to misclick).
Once Immortals enter the Vault, they must defeat the Shadows. This is the only aspect of gameplay on the Immortal side.
Rewards
If the Immortals successfully defeat the Shadows, they get some items and Hilts in varying quantity from 150 to 185. It is unconfirmed what the exact amount is based on but it is believed to be the Essentia stolen by the Shadows. The Hilts have a cap of 1400 per week. Furthermore the victorious Immortals also get prestige points that factor into ranking for commendations.
Every Sunday, Immortals can choose items from the vault. Only items that haven't been stolen by the Shadows can be claimed, and a higher contribution rank gives players priority in choosing the items.
History
In the September 21, 2023 update, the rewards were increased to up to 200 Hilts per defense and a cap of 1400 per week.