Imbuements: (Empty Slot, Empty Slot).
The Demon bosses Orshabaal and Morgaroth drop it. It's the third best one-handed Club Weapon available. After the latest updates this club weapon has been more available since you can loot it in the mighty demons surfacing from the abyss. Every demon boss so far has proved to drop it. Also note that even though it's one handed it's the second heaviest club weapon in game.
Khundahamar, The Thunder Hammer
The history of this hammer was best summed up by WoT:
"In the times of dread some of the best dwarven smiths were hold captive by the forces of Blog. They were forced to teach the secrets of smithing to Blogs children, the cyclopses. Kazrad Rockfist, a dwarven hero, braved many dangers to find the hidden underground forges. He sneaked in and managed to free the captives, but as they made a run to the exit, they found the steel doors sealed shut. With the rampaging cyclopses of Blog in their back the dwarf begun to pray to their gods and in the last minute they got an answer from the heavens. Kazrads hammer became blessed, and with a single mighty hit the hero shattered the doors, allowing all captives to escape. Wielded in many battles as a symbol of the fight against the cyclopses, the hammer was lost. The dwarves call this artefact Khundahamar, which means liberator but its only known as the Thunderhammer by the humans."
In-game only two such hammers existed, one was a gift from the gods to the person responsible for the 2002 real life convention, that hammer was later given to Pytru as a Christmas gift in the Christmas 2002. The other illegal gained by Warrax from the one shot behemoth quest, using his bought GM, Ender Speaker of the Dead. After Warrax's deletion, the hammer escape and was sold. The buyer lost more then hammer when he failed to heed the words from SGM Flattery, loosing his depot along with the hammer when CIP deleted the hammer.
A Hammer existed on Premia, entering through the Demon Quest that was located in today's Vampire Shield Quest that CipSoft created to get more people interested in Premia. The hammer was gained and sold by a Premian char named Morak.