Mysteries, Original Research, and Integration of Rival or Ancient magic? New Ranges, Durations, and Targets which can be discovered / integrated / taught as the results of minor breakthroughs, as well as some of the weird discoveries that are already documented in some of the sourcebooks? Items (and quests for items) that provide imspiration or insight?
Mod friendly architecture so that folks can insert their pet 'breakthroughs' into a json file that the game can recognize?