The Crona are constructs created centuries ago on another plane by a master artificer named Zor. Zor's goal was to craft vicious and bloodthirsty mechanical humanoids as his personal army to conquer his homeworld, but in a battle against a group of heroes, a gateway was opened that scattered the Crona across the multiverse.

Crona are made from metal so finely crafted that from a distance they are almost indistinguishable from a medium-sized humanoid. With exposure to the elements over time the outer "skin" of the Crona can change colour anywhere from a deep red, to bright green. To make them appear as fearsome as possible, Zor crafted them with stooped postures, animalistic faces, and jutting lower teeth like small tusks. All Crona have been programmed with a bloodlust for battle and killing, slaying anyone that stands against them.

The Crona can create more of themselves by consuming resources and joining together in mechanical couplings that produce smaller versions of themselves. These smaller versions take the programming of their parents, and over time consume more resources until they attain their full stature.