The Pact-Sworn

Hidden deep within the most secluded ruins of the old-world, magical radiation still resonates. Instantly deadly to sentient life, with enough time and exposure these waves of pure magical energy can also alter the fabric of reality itself. Cutting-edge Imperial technology has granted Imperial explorers the ability to descend into these oceans of paracausal energy for a short time, returning with relics imbued with unnatural power.
When inert objects are exposed to massive amounts of magical radiation, a tiny few are eventually turned into relics called Pacts. These items, mundane in appearance, have gained a strange sort of sentience, capable of communicating with those that bear them. Those that attempt to communicate with these objects find their physical abilities and even appearance altered over time, until they find themselves drawn to permanently accept these gifts. People who survive long enough to unleash the true power of these relics are called the Pact-Sworn and are incredibly rare, only a few have been recorded in the entire history of the world.
A true Pact-Sworn is an unmistakable and awe inspiring sight. Granted powers far beyond even the most talented mage, they can very nearly rewrite reality as they see fit. Legends tell of entire wars swayed by a single being striking down armies, reducing entire cities to dust, and even reviving the dead. Despite their sheer power, however, such beings vanish from history as quickly as they appear.
Pacts draw a heavy price for their use, sapping the very life-essence of their wielder and assaulting their minds with visions and voices seeping in from another reality. Over time, the Pact-Sworn themselves becomes a tear in reality from which magical radiation seeps, altering the world around them. Eventually their very soul is consumed and they are left utterly changed.
Among heretical scholars, there exists a belief that the first Emperor may have been one of the Pact-sworn, wielding otherworldly power and influencing the course of history in ways beyond mortal comprehension. However, such notions are spoken of only in hushed tones, for to question the divine authority of the Emperor is to invite swift and merciless retribution.