From Introduction:
Contraveners, also called Disrupters, are spellcasters who specialize in disrupting the spells of others. They are masters of counterspells, the most powerful of which gain renown for their ability to counter any spell thrown at them or their friends. Some contraveners use their abilities maliciously, striking from hidden locations to disrupt beneficial spells meant for the greater good.
In a group, contraveners gain appreciation for their ability to protect that group from active mystical harm. They remain spellcasters in their own right, however, and fill many of the roles of traditional magic users, depending on the ranks from which they come.
Many contraveners often find themselves in the employ of the wealthy and powerful, particularly those of a paranoid nature - or who have reason to fear magical attack. In some lands, particularly important events, gatherings, and trials may require a contravener be in attendance to avoid unscrupulous use of certain magics - charm person, invisibility, or immoral divinations.
The most common contraveners are equally clerics and wizards, each of which can benefit fully from the abilities of this class. Many bards also become contraveners, supplementing their countersongs with more powerful counterspells. A few paladins may even become Contraveners at higher levels, adding an entirely new layer of protection to the physical protections they often give to themselves and their comrades. It is very
rare that a sorcerer becomes a contravener, as they do not gain as many of the benefits until later in their careers.