Magic -
The world is filled with magic that most mages draw upon to perform their magic, the source of which are the Wells of Power. Some people have more magic internally than others, as evidenced that some mages can overtap their potential and cause self-harm. There are some races in the past that were very potent in magic as a natural trait, in the past. Other sources of magic are perhaps the use of souls (such as with Mechanists and some dark sorts), or through the Gods (mostly past, given the gods are offcially sealed off from the mortal realm).
Anti-magic, from what I remember as seeing, comes in three forms... Magic form of anti-magic, which essentially protects against magic or lessens its effectiveness... Null-magic fields, such as a machine that effectively created a dead zone of magic by drawing it all in (evidenced in a mechanist creation in LoR1), and natural anti-magic... which was ultimately seen in special races or individuals that either became a natural dead-zone for magic or were capable of drawing it internally.
However, looking at your trait, I'm not sure how well it will go over. Magic in an area, regardless of their focus, refined or not, or what side its being used on? That could get very disruptive, because saying its all magic... Well, you have it everywhere in the air. And then you have a fair share of allied mages and people with magical items. The way I would see it, this would either need to be moved down to a more contained AoE, where it would probably be most effective in melee situations... or when you are the target of a magical spell, friendly or not.
Uhm, and that's what I got. You'll need Brovo for official confirmation/deny and the full lay down of information...