Devilrings are ancient demonic artifacts that are used primarily for transportation.
Near the end of the Age of Isolation, the demons developed a form of technology that allowed them to tap into channels of energy that naturally flowed throughout the Universe. Monolithic rings were constructed to channel this energy, creating a means of long range teleportation that even the Angels couldn't surpass for eons to come. This lead to the creation of Hell's Gateway, a massive set of interconnected Devilrings that were able to reach all the way to Heaven, ushering in the time of Reemergence.
Most of the original Devilrings were destroying in the coming battles, and eventually the method of creating new ringspots was lost to time. Luckily, the portals they contained remained loosely tethered to the physical world. This meant that while new locations could no longer be fitted for rings, entrances that had already been developed could be repaired and connected with new rings.
Modern Devilrings take on many forms, most of them no longer requiring such large structures. However most have been recreated in the same classic shape or even use re purpose the old ruins to achieve the same effect.
Devilrings focus the flow of energy through physical space, allowing wormholes to be created. Any object or person that enters such a wormhole can then ride the river of energy to a new location.
Because the energy is constantly changing, a connection can only be made between certain rings at certain times. This however can be calculated by a skilled navigated by observing the relative positions of celestial objects. Even so, jumps without a Devilring to anchor the user to a physical location is highly unpredictable. This means that while teleporting to a devilring from an energy hotspot is technically possible, the reverse is never advised.