Sounds very good! -- I think this can be applied not only to the "Mirror" map (although it is especially relevant there), but also to all other map templates. No matter which city the Grand Mage is built in, the key spells always appear after the Xth, Yth, and Zth rebuild for each player (of course, these XYZ are purely random). Obviously, for all cities, finding DD/Fly will require a maximum of 5 rebuilds, since in Rampart/Necropolis/Inferno (cities with the minimum number of 5th-level spells), there are only 6 spells. This will significantly equalize the chances of cities in terms of Grand Mage building, and make Dungeon and Conflux more attractive in terms of Grand Mage development.