Earthenmaul

You have learned to shape the earth itself into a weapon of powerful destruction. You learn the shillelagh  spell, if you do not already know it. When you cast this spell, you can expend a use of your Wild Shape to instead target an object made of clay, rock, or any other unworked stone. You transmute a 10 lbs section into a powerful, two-handed maul of elemental earth, with which you are proficient. When you make a weapon attack with the Earthenmaul, you can use your Wisdom ability score in place of your Strength score. When used this way, your attacks with the weapon deal 3d4 bludgeoning damage and counts as a siege weapon when attacking structures. 

When you reduce a creature to 0 hit points with this weapon, you can use a bonus action to make an additional attack. 

When your shillelagh spell ends, the object crumbles to dust, rocks, and earth. You cannot use this ability again until you complete a short or long rest.