When a Mage performs magic that goes against the consensus reality (especially if done publicly), they risk incurring Paradox. This is the universe’s way of correcting the reality-breaking action, which can lead to catastrophic consequences for the Mage.
The Mage’s personal belief system explaining how they do magic. World of Darkness: Mage - The Ascension
Other antagonists include those driven mad by magic (Marauders) and forces of cosmic evil (Nephandi). Characters and Mechanics When a Mage performs magic that goes against