The Master Key allows for six doors to be unlocked without the need to locate the other key that unlocks them. This can save a heap of time if you are building up an online character (as you can skip parts). If you are new to the game, it is best to not skip these areas, at least at first.
- Undead Burg, access to Gold Pine Resin x3, held in a chest. Bypasses Residence Key
- Undead Burg, shortcut to Darkroot Basin and Havel the Rock. Bypasses Watchtower Basement Key
- Undead Parish, Knight Lautrec of Carim's cell. Bypasses Mystery Key
- Depths, Bonfire room. Bypasses Sewer Chamber Key
- New Londo Ruins, the gate between Blighttown, New Londo Ruins and Valley of Drakes. Bypasses Key to New Londo Ruins.
- Sen's Fortress, unlocks Big Hat Logan's cage and another with a Soul of a Hero. Bypasses Cage Key.
The Thief Class, starts with Master Key, Bandit's Knife, Target Shield and a set of Black Leather Armor.
For example, the Residence Key is used to free Griggs of Vinheim, but the Master Key will not open that door.
Similarly, the Cage Key or the Master Key can be used to free Big Hat Logan, but only the Cage Key will work on the cage elevator at the top of Sen's Fortress.