This article contains lore taken from Warcraft III: Reign of Chaos, Warcraft III: The Frozen Throne, the manuals, and/or official bonus maps.
Increases the Strength, Intelligence, and Agility of the Hero by 5 when worn.
Source
Thrall can find one in The Oracle, chapter 7 of the Warcraft III orc campaign, The Invasion of Kalimdor.
Illidan can find one in The Brothers Stormrage, chapter 8 of the Frozen Throne night elf campaign, Terror of the Tides.