- Choose it as a starting gift.
- Starting equipment for Thief.
- Purchase from Domhnall of Zena for 5,000 souls after he has relocated to the Firelink Shrine.
The Master Key can access bonus areas, as well as areas that would not otherwise be reachable. For example, normally reaching Blighttown would require trekking through the Undead Burg, killing the Bell Gargoyles at the Undead Parish, then fighting through the Lower Undead Burg, then the Depths with the Gaping Dragon; with the Master key, the player can simply take the shortcut through the elevator to the New Londo Ruins, the Valley of Drakes, and then Blighttown.
The implications of such activities are important. For example, accessing Blighttown early also means reaching advanced pyromancies and weapons, granting players disproportionately high firepower for their level. This can be a problem for starting players because they may run into high-level areas when they are not ready.
Players that did not take the Master Key as a starting gift can acquire it later from Domhnall of Zena after ringing both Bells of Awakening. However, at this point, the Master Key has mostly lost its usefulness, as the player will likely have already opened the majority of the doors the Master Key can open. The only uses it has after this point is in Sen's Fortress to free Big Hat Logan and obtain a Soul of a Hero. However, the player will keep the Master Key when moving into NG+, allowing them to use it in the next playthrough.
List of openable doorsEdit
- Residences in upper Undead Burg, save for that of Griggs of Vinheim (replaces Residence Key).
- Bottom of the tower in which Havel resides in Undead Burg. This leads to Darkroot Basin, and the door can be accessed from that side as well (replaces Watchtower Basement Key).
- Lautrec's cell door in Undead Parish (replaces Mystery Key).
- Door to the bonfire in The Depths (replaces Sewer Chamber Key).
- The passageway between New Londo and the Valley of Drakes (replaces Key to New Londo Ruins).
- The cage doors in Sen's Fortress (but not the elevator cages) (replaces Cage Key).