Lohn'goron, Bow of the Torn-Heart

Source
This item is a quest reward from The Cipher of Damnation (quest) which starts with Oronok Torn-heart. This is final quest of the Cipher of Damnation quest chain which starts with The Hand of Gul'dan (quest).

Trivia

 * Lohn'goron, Bow of the Torn-Heart is an Uncommon Weapon card in the World of Warcraft: Trading Card Game's Drums of War set.