Goblin Night Scope

Provides an increase to the Hero's line of sight radius at night when carried.

Source
Arthas and Muradin Bronzebeard find one in Dissension, chapter 8 of the Warcraft III human campaign, The Scourge of Lordaeron.

Arthas can find one in Digging up the Dead, chapter 2 of the undead campaign, Path of the Damned.