She compressed her domain...
The anti-magic field is a very domineering spell, suppressing all magic and supernatural powers by its very rules or concepts. Pure destructive power cannot affect the anti-magic field, and this spell affects everything within its range indiscriminately. This means that if a mage casts an anti-magic field upon themselves, they won't fear external spells, but they will also lose their own spellcasting ability.
However, the anti-magic field cannot interfere with divine presences, and thus cannot interfere with domains, as domains are the embryonic form of the God Kingdom.
