One of my weird goals is to eventually find a way to play Ars Magica with my friends who are very much not big on crunch. I can get my wife to play Grand Tribunal sometimes, but I miss a couple elements from the RPG. For me that's watching your covenant grow into a community and encountering uncommon or often ignored medieval myths and legends.
People have talked essential Ars Magica before, but if you had to boil down Ars Magica to just four or five mechanics, which ones would you include?
For me:
Art+Technique (although I'd probably do it the way Grand Tribunal does it: focusing on using them to create magical objects. My wife and the few players I've gotten to play the game really get into the "we're the real wizards who made the stuff from the later-garbled fairy tales" angle. I'm not sure if it was meant that way, but it sure works.)
VIS Collection
Grogs (but a pared down version: I love named hit points that can get married and have more named HP who might become apprentices or maga themselves, if they survive)
Voting (this is, to my mind, the core mechanic of the Grand Tribunal game and what makes it interesting: the changing values of spells and artifacts due to the fickleness and intrigue of Hermetic Culture.)
...and a stripped down version of the economy/development point system from City and Guild. I think it was City and Guild. I have notes from someone else's campaign, not the book.