The game does not always work, sometime it frozen in middle of battle which cost energy for nothing. Energy increase as you go along with missions but level up does not increase energy cap which does not make sense at all. When burn up all energy, arena is almost pointless - get fame only to unlock cards (most of arena cards do not turn me on, maybe only one card interested - need to add reward such as gold) Then we have reason to do arena to buy overpriced sets of cards which we mostly will get same card again.
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