I'm curious as to what the home bonuses will be. Perhaps your mark is determined by what area you are in? In the no-mans-land, marks would probably be choosable, but as soon as you enter another elemental land, your mark becomes that element. That would take more planning; you'd have to decide what kind of deck you would make in order to successfully invade another territory. If things could be bought with electrum, perhaps buying an increase in deck size or taking x amount of cards that you can switch into your deck (I'm assuming that each player has a certain amount of cards when they leave their capitol, and that they can't add more cards to their personal "vault" unless they buy them or return to their capital) and another possibility is to buy a mark so you aren't affected by elemental lands...
Just some thoughts.