In the competition, the challenged mage begins by creating a magickal effect. The challenger then has to outdo him, either by greater power, skill or style. The competition continues until one mage is unable to perform a greater feat of magick. Quite often the place of the certamen was regulated by chantry rules, to minimize the risks to the chantry or non-combattants. The magick has to use the same or higher levels of spheres as last time, decreasing the power is generally regarded as failure unless it is done very stylishly.
Style is important, especially if the mages are closely matched.
Coincidental effects are often regarded as a bit unworthy if the opponent uses vulgar magick, but sometimes a clever coincidence can decide a competition. The challenged mage performs a magickal act. The challenger then has to do a comparable act that gains more successes than the challenged, who then has to outdo him and so on. He must use spheres at the same level or higher than his opponent. Moving up to the next level of the spheres do not require the mage to gain more successes as the opponent, as long as the result is perceptibly more advanced.