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.
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.
This 2 page PDF contains all the information about the Contravener Prestige Class that you will need to use it in your game, including potential plot hooks and ways to use it in a campaign.