The Orb of Detection

(   The Orb of Detection
Base item	crystal ball
Affiliation	lawful Archeologist intelligent
When carried	telepathy magic resistance half spell damage
When applied	selective object detection
When invoked	toggles invisibility
Base price	2500 zm
Weight	150

The Orb of Detection is the archeologist quest artifact. It is the prize for completing the archeologist quest. It is lawful for wishing purposes. Its base item type is a crystal ball.

When carried, the Orb confers magic resistance, telepathy and half spell damage. Invoking the Orb toggles invisibility on or off.

In UnNetHack the Orb of Detection is replaced by the Itlachiayaque.

Encyclopedia entry

This Orb is a crystal ball of exceptional powers. When
carried, it grants ESP, limits damage done by spells, and
protects the carrier from magic missiles. When invoked it
allows the carrier to become invisible.