I wanted something ... original.. I think. So I sketched this construct.

Powered by the void energy, serving as it's core and main body at the same time. The energy is shaped into a sphere and kept in place by the enchanted metallic ribs build around central point. Arms and legs are not directly attached to the main body, instead they are floating closely to the construct.
The nozzle in the front serves as a focusing point for Gamma-Ray Burst of immense power although it consumes significant amount of energy which reduces the size of the core.

Core can later be recharged through a ritual which changes the matter into energy and allows the core to absorb it. This would also be possible without ritual by removing the metallic ribs, although this would remove the safety measurements keeping the Void Core from absorbing the matter from its surrounding.

Also destroying the ribs would lead to uncontrolled absorption of matter and energy by the core and will lead to expansion of the sphere. Some scholars believe the core would expand to some point and later collapse focusing all energy in the single point and then explode releasing unbelievable amount of energy, destroying everything withing many miles radius from the point of collapsing.

Makes sense? No? Think... MAGIC!