That's a very interesting suggestion. When you take away the upgrading of buildings in brawls, they give an image of how good your skills are because you play against people who have the same limitations of level. On the other hand there still are differences in cards even in these games. In tradtitional games, there are such skill modes where people have a selection of cards that are identical for both players. The one who makes the best line up with that, wins the game. I believe this would be quite cool and a way to level the playfield for everybody. It could be a tournament style for example.
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Brawls are the most fun and implementing some kind of skill mode could indeed be done also in Tournaments. My main issue is just that at no point the game ever gives you that sense of accomplishment of outplaying someone. I really hope they are at least considering doing some kind of skill mode at some point in time.