Paradox is the force that limits the power of Mages. Just as the collective beliefs of mankind create and shape reality, an act of magic that violates those beliefs about how the universe works generates paradox, and if too much paradox builds up in a mage, their power can rebound back violently, causing injury or death to the Mage. Extreme paradox backlashes can even produce powerful explosions, as when Bruce Von Eisenstein intentionally produced a massive paradox backlash to destroy the first Bug invasion of Earth in 2001. If a magical act is witnessed by unawakened humans, much more Paradox is produced than if it is only witnessed by other Mages. In an era when everyone, even the unawakened, are aware of the existence of Magick, Paradox backlashes are much rarer and less dangerous than they were before Gehenna.
Behind the Scenes
This concept is from the game Mage: The Ascenscion, one of the White Wolf games which Tech Infantry was originally based upon.