Its uniquely fun but I hate it. You go with the story, defeating bosses with near impossible playstyle to beat, just to earn jackshit with rare cards that can only take you so far before your hurled across the arena by a pathetic shadow mode spamming boss. I see shadow fight as a way to relieve stress - not that it's effective at all to be honest. The constant trial and error to beat a boss will just be adding on my bottled up frustration which will just help you earn a 1 star rating from me.