Sulfuron Hammer

Sulfuron Hammer is an two handed mace, used primarily for the purpose of crafting Sulfuras, Hand of Ragnaros.

Source
This item is crafted with Blacksmithing (300); taught by Plans: Sulfuron Hammer, a quest reward from A Binding Contract.

As an ingredient

 * Sulfuras, Hand of Ragnaros

Background
Ragnaros wields a massive weapon named Sulfuras. It is far too massive for most mortals to even dream of wielding, even if they could somehow defeat the elemental Firelord. However, fanatical followers of Ragnaros found a way to craft hammers in its image. Each requires an eye of Sulfuras, and these lesser weapons are known as sulfuron hammers. A sulfuron hammer appears to be a smaller version of Sulfuras. It is a spiked, flaming red warhammer. The hammer is crafted entirely from elementium, with an eye of Sulfuras embedded deep in the hammer’s head.