Reality is not always consistent. There are times when it is more susceptible to manipulation than others.
One of the important things for roleplaying magic, in my opinion, is working out how the wizard sees magic working and how they get their mind into the state where they’re working magic. This is mostly a roleplaying issue, but it has repercussions in the special effects of a wizard’s magic and the manner of effects they can create with the same Spheres as a very different style of wizard. (It also defines what it takes to restrain one from spellcasting— tie them up? gag them? take away the brushes and inks?)
Player character wizards are not required to put a lot of effort into studying the occult, but they should work out a background against which their wizardly activities work.
True Magick is the most dangerous of all powers to wield: it is capable of the strongest effects, and carries the strongest penalties. Only one person in a million is capable of wielding it effectively, and the others who try and fail tend to die in very interesting ways. Paradox is the name that mages give to the immune system of the universe that rejects overly harsh attempts to disturb the natural flow of the cosmos.
Most sane practitioners of True Magick learn to work within the flow of the universe, performing feats without defying local rules of causality. This manner of magic is called coincidental, since it can pass for a coincidence.
Blatant magic, on the other hand, can get away with amazing feats, up to and including teleportation, time travel, and the formation of pocket realities. (Such realities are vastly more stable when they are anchored in the Netherworld, and time travel is much easier to open junctures rather than closed ones.)
One of the advantages of control over the universe, whether through the collective unconscious, feng shui sites, or having the Invisible Clergy on your side, is that your particular style of magic can become easier to use... and your opponents’ more difficult.
The universe possesses a certain intrinsic structure that is susceptible to manipulation in a variety of ways. When such methods are easily repeatable by a machine or a relatively untrained person following explicit directions, they are referred to as “physics”, “chemistry”, or “mechanics”. When the means require esoteric training and honing of the will, they are called “magic”.
Hedge magic usually works within the limits of the universe, and qualifies as a coincidental activity. It is less versatile than True Magick, but tends to cause less of the disturbance called Paradox. Hedge magic applies to the activity of most of the occult underground, as well as the more spectacular powers of magical creatures, arcanowave technology and the more blatant fu powers.
Hedge magic can operate coincidentally even when its more blatant effects would create Paradox. Such magic can manifest as incredible luck and timing, rather than blatant sorcerous might.
The core powers of magical creatures, from the undead to shapeshifters. (Such creatures can learn to wield magical power on the order of hedge magic; it is quite rare that they can master True Magick.)
Paradox manifests in a variety of ways. The most mild is a juncture modifier, where a particular form of magic is easier or harder to make use of. (Mechanically, this is just a bonus or penalty to action values.)
The next level up is paradox backlash. When reality is strained beyond a certain point, it can suddenly snap back to its normal configuration, releasing a great deal of magical energy. This will tend to ground out on the hapless wizard who casts one spell too many. This can manifest as anything from apparently horrible luck to blatantly counterphysical effects that result from the pendulum swinging too far other way.
At the worst, the universe’s immune system can simply form a cyst around the aggravating magical activities and wall it up into a pocket reality with extremely bizarre rules of existence, called a Paradox Realm. The reality will usually dissolve at some point— either after the passage of a certain amount of time or the solution of an enigma that is holding the reality together. It will usually dump characters out into the location from which they were pulled, but has been known to dump them out into the Netherworld or even other junctures. Some Paradox Realms seem to be long-lived, sucking in individuals guilty of the same crude manipulation of reality.
Paradox is measured by a combination of paradigm strength and juncture modifiers. Paradox policies include:
Note that it is very difficult to achieve a paradigm where basic chemical reactions like gunpowder and basic electromagnetic phenomena like semiconduction do not work. As much as the Lotus would like to make railguns and assault rifles unworkable, they don’t have the combination of power and vision to create an alternative to quantum physics.