[@Nightknight]
I'm glad you asked.

While I have no wish to spoil all the mechanics of magic before the story even starts, what people immediately observed about it was that it responded directly to their thoughts, in effect breathing life to their imaginations. The thing is, magic has no mind of its own, so the depth and complexity of a spell depends entirely on the depth of the imagination that spawned it. Moreover, it responds to natural laws to some degree, so the straight-up creation of new matter is far more mana-consuming than rearranging existing matter to fit your needs. A good mage will therefore 1) imagine his spell to the best of his ability and 2) consider the most efficient available resources to produce it.

Since we'll be working with a fully developed magic system, I may introduce NPCs from time to time to illustrate spellcasting techniques I came up with.