An Energy Core is a rarely seen piece of technology, which is known to be full of powerful energy. This energy is partly infected with Quaza, the element that makes regular Hero Cores.
The Energy Core originated about 3 years ago, where an unknown villain somehow created one using infected Quaza. He documented his discovery to share it with the world. However, only Airhawk and a couple of other villains have figured out his invention before he was killed.
An Energy Core is made with a glass sphere, inserted with dark energy and infected Quaza. Then, mixing it all together. Once it is inserted in the torso of a hero or villain, it cannot be removed without the destruction of the core itself, as well as the cost of killing the wearer.
Only a few people have been known to wear the energy core. One is Airhawk, who replaced his original core with an energy core. Everyone else that may have used the energy core has not yet been documented.