Magic Negation is a skill practiced by mages, though not used to its full extent until 401 A.G, when it was utilized to protect cities from the Wrath of the Gods.
Magic Negation is used very rarely in magefolk societies, as it is seen as rude to block someone from using their abilities. Most mages will only use it out of necessity, and it is best used by healers who are softening the effects of mage scars. In a magic-heavy place such as Selkros, there are some mages, particularly those with many mage scars or who posess mage sight, who need to find a place away from the magic.
Historically, magic negation had more important uses. During the Wrath of the Gods, those with the skill of magic negation were able to defend people and cities from the gods, though at great cost to themselves. In 401 A.G, a few mages banded together and found a way to disperse the affected magic between them, so that none of them single-handedly bore the weight of magic of that level. Mage shields were common around Marisen and Nitheme as a way of protecting people. During the mage wars and before the Weeping Plague, the powers used to create mage shields were combined with magical constructs to create physical walls that could block armies from entering places like Selkros. Mage shields are still used in some places today where hiding from other mages is needed. Some rogue mage dens in Marisen utilize them to block their magic output, strengthening them with runes discovered by Rusar practicioners in Audhyll.
One reason magic negation is rarely used is because of the complexity and cost to the mage who uses it. It involves both being able to understand the magic they are trying to negate, as well as being able to withstand the magic for as long as its being redirected. For that reason, the only sucessful mages who have mastered the art are those where the skill is an innate ability and not a learned one. Those who can negate magic are more likely to have larger mage scars, but they are also able to master other skills easier. Since magic negation involves understanding the skill you are negating, mages can learn to reshape their own magic in that form and mimic the abilities of other mages. Therefore, those who can negate magic are among the most powerful mages in Maeovis.