I got the first box (War of Indines?) as an add-on to the Minigame Library Kickstarter (my first exposure to this vendor). Game blew my mind.
I have no idea what is compatible with what anymore (I thought Devastation was, but I missed that Kickstarter, and now I see there's Remastered stuff?), but I'd like to pick up the other expansions/whatevers down the road. I'll need to do some factfinding going into the Millenium Blades pledge manager add-on bonanza, whenever that happens.
War of Indines was their first Battlecon release, since then they a while ago made a Kickstarter for a remake of that first game to make it up to quality with their Devastation of Indines. All Battlecon games are compatible with all others. You probably have the War of Indines edition they now call "Classic" which wont ever be printed again. It can be used together with any other Battlecon set as normal and intended. The new upcoming remake of War for Indines will have updated art and card text (most likely also some changes to the balance of the fighters).
So, in short, no matter what you get, you only need one of the Battlecon base games (War, Devastation or Fate) to play and can get whatever expansions you like and also combine everything as you like, each base set comes with unique fighters so you are free to get the others to expand your roster.