I agree with others that adding AM mage to a stereotypical fantasy setting won't work unless the assumption is that AM magic is new.
That said the more I ponder this question the more difficult it gets.
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What type of stories is this world meant to tell?
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What kind of history does this world have?
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What kind of inherent conflicts and obstacles are there?
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AM magic as is or modified?
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If modified, what modifications?
Etc
Personally I'm a fan of mageocracies ruling the world and fighting with each other.