The Roil

CONCEPT
The Universe is finite. It is cosmically vast, to be sure, but it does have an edge, an endpoint beyond which reality as we know it ceases to exist. Beyond that edge is the Roil, a truly infinite expanse of raw, energetic potential. What we think of as the Big Bang is actually more like a Tiny Hollowing within the Roil; our unfathomably huge Universe is merely a microscopic bubble formed within the Roil.
 
Bubbles like these exist everywhere within Roil, an effervescence of creation, where fragments of that cosmic potential briefly solidify into a set form of reality before crumbling back into non-existence. In the Roil, these Reality Bubbles last for a comparative instant; within them, eons upon eons pass for as the Universe within forms, evolves, and eventually dies.
 
The Roil exists in countless dimensions. While it is technically possible to travel to it via reaching the edge of the universe, this is impractical for numerous reasons. However, any one can reach the Roil from any physical point within a Universe via dimensional travel. Indeed, with the proper protections, it is possible to use the Roil as a medium by which to access other Universes entirely, as well as different points within a single Universe.
 
This is the secret of hyperspace travel, time travel, pocket dimensions, alternate timelines, and other such deviations from the standard reality.
 
The Roil is also the secret behind the reality breaking powers of superhumans, magic, and breaker technology. The Roil being a realm of pure potential, it is capable of rewriting existence as we know it. By channeling the energies of the Roil, one can perform impossible feats. Civilizations that manage to achieve reliable access to the Roil have the capacity to effect God-like change in the Universe.
What follows are different takes on how the power of the Roil might be used in different sub-settings:

ROIL CRYSTALS
Roil Crystals are a solidified form of Roil energy, and is one of the more efficient ways to store and utilize such powers. The Crystals act as both artifacts of power that allow the holder to bend reality to their will at a local level, as immense power sources for the energy needs of advanced civilizations, or as critical components for the stabilization of habitats. However, even the most advanced civilizations cannot fully control this resource on a large scale, and thus, they cannot simply overwrite the whole of the Universe as they see fit.

CONCEPTUAL MAGIC

Indirect contact with Roil energies leaking into a reality can cause physics-defying phenomenon commonly referred to as "Magic". Magic in these settings tends to form in response to sapient thought, and however these forces express themselves, the mechanics of any given magic system are tied to the cultural folklore, suspicions, wisdoms, or correlations of a given civilization or species. The more advanced a civilization is, the more elaborate a Magic system may be. Some systems are very precise, while others take a more nebulous and adaptable form. In any case, these systems have a heavy use of metaphorical mechanics, with symbolism being the catalyst for effecting change. The ultimate effect is that each Magic system creates a deviant framework of it's own physics system that it then super-imposes onto reality, in such a way that it is only accessible by those who have awakened to the power.

Conceptual Magic systems are capable of warping reality in specific ways aligned to the concept, and depending on how far they spread, can impact civilizations while simultaneously solidifying the concepts they are based around into place. In the worst cases, civilizational progress can stagnate as certain Magics self-reinforce a rigid understanding of reality.

Concept Magics are usually limited to a certain theme around which all their powers hinge. An example would be Snow Magic which allows manipulation and generation of snow in physics-breaking ways, but cannot extend to control of water or mist or even solid chunk of ice. Meanwhile, Nature Magic could allow one to manipulate a vast array of aspects of Nature, from all the classical elements, to animals, to plants and fungi, to the weather, etc.

Worlds that have access to numerous Concept Magics are more capable of cultural adaptation and progress, as no one Magic dominates over the other to enforce itself onto the civilization. These Magics may even end up adapting over time to become more rigidly defined unto themselves, breaking down into more scientific methods of execution and mages and scientists alike refine and distill the Magic down to a basic level of educational understanding. In the process, a civilization can subconsciously warp a Concept Magic into a mechanized system that becomes as easy to use as common technologies. This is how most of the Stable Magics that are developed on certain worlds form, i.e., Alchemy that operates on extremely specific chemical formulas, Runic Etching that utilize extremely precise crafting, all are descended from much looser forms of Transmutation Magic and Rune Magic.

SUPER BEINGS

Occasionally, a living entity, usually a sapient being, will come into the briefest of contact with a Roil phenomenon, and become a unique form of superpowered entity unto themselves. Such super entities can have powers as low-grade and specific as having a minor physical boost, such as low-yield super strength, or can result in entities with nearly godlike power. The phenomenon is rare, but given the sheer number of lifeforms out there, any given planet hosting life, and especially any given civilization, is likely to host tens to hundreds of superhumans, possibly thousands depending on how closely tied to the Roil their civilization is.

Worlds with super beings formed through Roil contact tend to come about in one of two ways: a singular world-spanning "event" whereby a planet or plane is struck with an indiscriminate wave of Roil energies, instantly transforming multiple beings at once. Or, a slow, imperceptible leak of the Roil creates a period of time throughout a world where seemingly normal accidents or disasters or scientific experiments will cause people to "trigger" into obtaining powers.

What affects this has on the world depends on how great the scales of power are, and what the civilizations they are inflicted on do with them.

BREAKER TECHNOLOGY
Breaker Technology is any machinery advanced enough to access and fine-tune channel the reality-warping energies of the Roil. Usually invented through the continuous evolution of quantum computing or extra-dimensional exploration, once the code is cracked, B-Tech development accelerates at monumental speed, usually much faster than any species is prepared for.
 
Within a hundred years of discovery (or less), most civilizations using Breaker Technology rapidly advance from being able to control the resources of their whole planet, to those of their entire solar system, and are well on their way to spreading across their galaxy.
 
B-Tech enables direct manipulation of matter and energy to a degree only previously seen in the more fantastical renditions of science fiction. Infinite energy sources. Replicators capable of converting stored energy into any form of matter, including new, previously impossible materials. Instantaneous travel across stellar distances via wormholes. Medical and robotics technology capable of greatly extending lifespans and modifying organisms. Fine-tuned manipulation of fundamental forces such as gravity and electromagnetism. Gateways to alternate dimensions and timelines. Nanomachines capable of high-speed construction and maintenance. Megastructures of physics-defying scale, capable of housing hundreds of worlds worth of habitable land. Civilizations with access to such miraculous inventions possess god-like power over their environment.

However, B-Tech has one fundamental limitation: the energies of the Roil do not work so well with living beings, especially not sapient ones. This is because the chaotic energies of the Roil are nearly impossible to control through direct contact. The Roil reacts too readily to the chaos of the sapient mind; the many conflicting emotions and imaginings and presumptions a person holds at any given moment means that direct attempts at self-evolution with Roil energy result in radical and often horrific mutations. Thus, the Roil can only be safely channeled through mechanical methods, and with supercomputers specifically designed to account for its many possible effects.