I'll have to work on the types of magic as well as the philosophies, religions, political systems, etc. followed by the mages. (There will be a range in this place, but which types are prevalent?) Also, where do they get the power for their spells? There must be a cost to magic. What is the cost and who pays it? I've considered having the cost be metabolic -- they must eat quite a bit to keep up the energy. (This could be something of a natural limit on truly dangerous earthshattering spells because no one could eat enough food to cast the spell.) The prison feeds them well but still not as much as they really need. They are careful to keep them at a lower level of energy -- what would amount to a keeping prisoners fed at a subsistence level.
The Fiction Writing workshop at work will be different tomorrow. We didn't get copies of the stories in time, so Matt asked if we wanted to cancel or if we wanted to do brainstorming or Q&A (or writing exercises). Luckily, brainstorming and Q&A got the vote. (It would've been a shame to cancel, there is always something to talk about concerning fiction writing!) Maybe I'll bounce some of these ideas off the class tomorrow. Plus some ideas about wards and stuff to keep the mages in line in the prison.