Eberron: Soaring Skies of Khorvaire
It's a giant hammer that lets you swim through the ground like a fish.
Base Attack Bonus:
+0: Relbmet’s Wrath grants an enhancement bonus to-hit and damage equal to your BAB/4. (To a maximum of +5 at L20.) It can be wielded with two hands by a Medium-sized creature without penalty.
+1: Whenever Relbmet’s Wrath is used to damage an item or object, it is treated as a critical hit which is automatically confirmed.
+6: You can the earth glide of an earth elemental for a number of rounds per day equal to your Base Attack Bonus. Activating and dismissing this ability is a free action. Usage of this ability need not be continuous.
+11: You can use wall of stone 1/encounter with a caster level equal to your Base Attack Bonus.
+16: You case use earthquake 1/day with a caster level equal to your Base Attack Bonus.
This masterwork Large maul’s head is fashioned from a bound earth elemental, inhabiting an arcane prison of Khyber shards and animated stone. Legend says that a great hero once succeeded in sundering an entire world inhabited by catfolk with a single blow of this weapon: As there are no known worlds beyond Eberron, it’s obviously allegorical.