The Battletech Warhammer is my all time favorite mech, known as the Tomahawk in Macross and Excalibur in the Robotech series. Whatever the name it's going by it's just an awesome design.
As I already have the destroid legs built for the Rifleman/Defender it was a simple cut and paste to add it to the Tomahawk. I finished blocking out the torso and arms, I'm currently at about 5-6 hours of build time. It's been going much faster than the previous mech so I may have it finished up within another day or so.