User blog comment:IamJakuhoRaikoben/Chapter 442: The Law of Space, Review./@comment-24784846-20150629162147/@comment-24546844-20150629181937

It's hard to know how his magic works just from this chapter but from what I can see: Erza's magic summons her weapons from different dimensions so it manipulates space to allow them to "enter" so he can negate the space manipulation aspect and thus the magic. Same for Lucy: by not allowing her to open portals to the CSW he directly negate her summons. For Mest, assumng his magic works like Nightcrawler's, is the same: Mest cannot manipulate the space around himself to "leave" the space and cannot open new doors to come back. Natsu's fire is different in that it comes from the magic within himself not from another dimension so he cannot negate it.

If I'm right his magic creates a sort of "spatial stasis" in a determinated territory that cannot be modified by magic means except by himself or by a superior magic power something that Minerva may or may not be able to do. Of corse I may be wrong. There's no way to know for sure unless it's explained further.