Density control among other things isn't an often talked about ability nor is Changing the thickness of an object. But this ability has apparent attacking and protecting assets. If someone picks a fight, you may choose to expand your weight to become a concrete force, or perhaps you can become so light that all punches go straight through you. Then there's the ability to reduce the weight of heavy objects, making them as easy to move as a pillow. Pull off that kind of trick while pumping iron at the gym or at the beach, and you are sure to get noticed.