There will be a few maps with pre-made settings that will be used in tournaments and in a few sponsored gyms but outside those areas terrain will be randomly generated if the one who initiates the battle wants it to be as such. Mostly though I will tend to stick to the more preset map styles. As for terrain advantages and disadvantages, there will be a few which will effect how easy it is to defeat an opponent or how hard it will be. For example, I intend on having a hill map which will make it harder for melee decks to hit unless they move in close but allow ranged decks more opportunities to hit their opponent. This does not mean that we have to move across maps but I will offer info on the map before beginning a battle and the options you have to get a better chance at winning once it begins. Right now I am working on which stats go to the basic decks.
Side note: You characters can have two decks with them and switch out a damaged deck for their separate deck while the main regenerates