Summons an Ice Revenant. The Ice Revenant lasts 180 seconds.
This section concerns content exclusive to the Warcraft RPG, and thus unlikely to be canon.
This item looks like a chunk of ice carved from the purest crystal. When held, it seems to draw body heat from its owner, chilling his flesh in a notable, but harmless manner.  (M&M 146)
Kael and Lady Vashj can find one in The Crossing, the secret level of the Frozen Throne alliance campaign, Curse of the Blood Elves.
Arthas, Kel'Thuzad, and Lady Sylvanas can buy them in The Frozen Throne Scourge Campaign Chapter 1 - King Arthas.