Unique item

All artifacts are unique, but there are four objects which the game specifically refers to as unique items on the discoveries page:

• The Candelabrum of Invocation
• The Bell of Opening
• The Book of the Dead
• The Amulet of Yendor

While these are also commonly referred to as "invocation artifacts", they do not count as actual artifacts for purposes of artifact wishing, as the player is always guaranteed to encounter them.

Distinguishing from other "one-per-game" items

Artifacts are not unique items in the sense of this article; they are specially named variants of their base item with additional benefits. For example, the Eye of the Aethiopica is a named amulet of ESP that also provides faster energy regeneration among other extra powers.

While Stormbringer is the only runesword and the Tsurugi of Muramasa the only tsurugi that can normally be generated in a game, neither counts as a unique item; it is possible to find a non-artifact runesword or tsurugi in a bones file (if the artifact has already been created), or by wishing for one.

Variants

EvilHack

EvilHack adds several other unique items:

• The Magic 8-Ball
• The Bag of the Hesperides
• Lifestealer
• Butcher
• The Wand of Orcus

All of the items are treated as artifacts - as with the invocation 'artifacts', they are guaranteed to appear and thus do not count towards the total number of artifacts in a game.