Mallet of Zul'Farrak

The Mallet of Zul'Farrak was once needed for players to summon Gahz'rilla, a boss in Zul'Farrak.

Source
The steps to create this item were explained in the Ancient Tablet, a random drop in Zul'Farrak. First, you needed to head to the Altar of Zul in the Hinterlands. At the top were two mobs, Qiaga the Keeper and Morta'gya the Keeper. The Sacred Mallet dropped off of Qiaga the Keeper.

Next, you needed to go to Jintha'Alor, namely, the altar at the top. You had to fight your way through level 45-50 mobs on the long trek up. At the top is an amphitheater, with the Altar of Jintha'alor in the middle. On it is Elder Torntusk, a Horde NPC. After clearing the mobs, you had to stand by the altar and right-click on the Sacred Mallet. This would transform it into the Mallet of Zul'Farrak.