What would magic do?

[s/LaSH]

It depends on the sage, I guess. If he's well-funded, he's probably the son of a lord somewhere - instant political might for one faction, bloody turmoil for a few years, new king on the throne, little changes for the peasants beside a few more scorched fields after each battle. If he's a priestly scholar (and face facts, most scholars were priests or monks until a couple hundred years ago) he's associated with a religious order; they either burn him as a heretic or exalt him as a great saint. If he's a crazy hermit on a hill somewhere, nobody cares and his hill is suddenly a whole lot quieter that it once was, while he runs around pointing at rocks that blow up or turn into rabbits. The occasional quester for knowledge comes to his door, and magic spreads out very slowly through a caste of wanderers and bards. Which in turn either creates an exalted wanderer caste, or all the wanderers get stoned on sight and civilisation enters a new dark age in that region as everyone bars their gates and looks suspiciously at anyone who might be from out of town.

 

[Praeco]

This idea pretty much presupposed a monotheistic society (which while definitely outside D&D tropes might be pretty interesting), as struggles between traditional D&D gods would likely negate the unified power of the clerical caste that I'm using as a basis.

If religion holds much of the political power, the magic had better be divine, or the first would-be sorcerors would likely be identified as heretics and get burned at the stake. If the magic is divine, it would surely affirm thigns like divine right based on magic use, leading to the possible establishment of a powerful theocracy.

If it is arcane magic, I could see a power struggle between secular rulers who want to harness this power, and the religious class who would prefer to keep it under wraps, as it supposes power can come from some place other than whatever god they worship.

Another good thing to think about is the appearance of magical beasts. Did they exist before? Have they just started to appear along with the birth of magic? Where are they coming from, if the latter is the case? I could imagine a situation where a portal to the divine realm, or another plane, has opened up, leaking both power and magical beings into the campaign world.

So you've got political intrigue, the possibility of civil wars, and the mystery and danger of the appearance of new and frightening beasts.