Technology is one of the driving motors of cultural change. A Technology is really just 'the way people get things done' though a body of knowledge. Active magic (the kind in most games) is nothing more tha a way that people get things done though a body of knowledge.
I want you, if you are old enough, to think about all the changes that have occured in your lifetime... how different the world is today than it was a decade or two ago, just because of technology - and the changes in society based on the foundation of those technologies.
If you are not old enough, think of two things... one) a world without an internet/ web/ or computers that weren't any better than 25 cent calculators and two) how unable to deal with new technology and the world attached to it that most older people (and how you have to break most simple technology down into baby steps for them)
So imagine the impact on your world, initial and eventual, of a new form of magic emerging.
It could come from a Deity (like in Iron Kingdom), it could come from a Demon (and who determines that label?), or from one innovative/ enlightened person (Hermes Trismegistus (or a host of other names applied).
It could be one extremely useful spell (super fireball or a 2nd level spell that creates Golems/ jacks) or an entire range of magical techniques (Top Magic). How will the world change because of this new type of magic? People will respond, either by using it or trying to stop others from using it. What can be done now that could not be done before (or done as easily)?
Would this new power threaten the status quo? It would upset the magical community some. Masters of all magical knowledge no longer are masters. (Just think of old unix programmer/ managers vs newer Window* programers/ managers vs newer elite programers). Depending on its power and who can use it, it might disrupt the religious, governmental, commercial, and social structures that exist. Those groups would respond and retaliate, to maintain their hard won position in society. It could create new groups, that too would disrupt the status quo.
And what are the common's people response to all of this? Do they know? Do they care? Do they believe the lies the various organizations of status quo might promelgate? Do they believe 'the truth' of the new practioners of magic?
So, yesterday a new form of magic was discovered/ invented on your world (or any world), what will happen from there.