| Item | Ultimate Key |
| Description | Opens certain doors that would otherwise remain tightly sealed. |
| Location | Cathedral of Light |
The Ultimate Key is inside a chest in the Cathedral of Light, in the third chapter of the story. This is an optional item and it’s very easy to miss, but you’ll need it to get some unique items.
Warning: this guide contains spoilers for Dragon Quest VII.
Reaching the Cathedral of Light
The Cathedral of Light appears on the map after reviving The Almighty. But you still need to do some tasks first before being able to go there.
After reviving him you’ll be at the Shrine of Mysteries. Go to Pilchard Bay and talk to the chef inside the ship.
Exit the ship and a festival will start. Talk to the old man at the entrance of the town and go to Estard Castle. Pick any choice when talking to King Donald. After a cutscene, you’ll be back at Pilchard Bay.
Note: Before heading to Estard Castle, it’s a good idea to make sure that Sir Mervyn is well-geared and able to defend himself alone. In an hour or two, he’ll be separated from your party for a while and you’ll have to control it.
Talk to Pollock at the deck and then to the chef inside the ship. Leave the ship, talk to the mayor and head back to Estard Castle.
Talk to the chancellor in the throne room, and then go to the dining room on the floor below. After yet another cutscene, your party and the king will fly in the Skystone to the Cathedral of Light.
Finding the Ultimate Key
The king will leave your party alone for a while, so you can explore the cathedral for a while.
Exit through the south stairs, go to the first plant and head to the northeastern room. From here, go up again and take the exit south.
Circle all around the cathedral going through a corridor, a room and another corridor. When you reach the northwestern room, take the stairs down.
You’ll be at the cathedral’s prison. Open the blue door on the northern side of the room. There are two chests in here. One chest has a Haywire Helm, and the other has the Ultimate Key.
The Ultimate Key is yours! You can open all doors and chests in the game with this key. You can try opening the prison cells in this same room, and then break the pots to get a Seed of Magic, a Seed of Life and a Seed of Strength.
Note: If you don’t get the Ultimate Key at this moment in the story, you can still get it later, when you recover the Skystone and can go back to the Cathedral of Light. The only difference is that the entire building will have roaming monsters.
