Magic
Just because magic is incredibly rare does not mean that it's something special. Well, it IS special, because it is rare, but so are diamonds. Many a Wizard probably would rather own a large diamond mine than to have their spark. The point is, with great power comes great political intrigue.
While many noble houses admire and want magic, some find it an abomination against Rahn and would snuff any magic user out if they could and a few don't even believe in it. Since magic is a high value commodity, it can be important to use magic unseen as well as hiding traces of handiwork for other mages.
Magic is "naturally" incorporated with the fabric of the cosmos. The part that is used actively is leakage and higher concentrations (like fossil fuels in a way). Anti-magic fields come in different shapes and sizes, including those mortals who seem negate magic. Most anti-magic fields created by magic through conscious effort or naturally occurring usually just manage to negate the said leakage and concentrations of it. This is what professional users call "no magic" and what they are aware of. However, it is also possible to create a complete magic nu, where there is no magic. Most sentient beings will in such a situation fall into a coma, and random chemical reactions may happen as the magical lattice is not affecting those molecules. This is naturally occurring, but not conducive to any form of life (or order): a bit like black holes and just as unexplained in detail.
In the same way normal matter is affected in a limited way in a total magical null, the magical lattice behaves erratically around black holes.