The biggest flaw is mythics. If you don't know, their mythic system is every pack you open can cointain a mythic card in it. The thing is its a really small chance. Legendaries are less than 1% so mythics is even smaller than that. Thats fine and all except that they are so strong that they will win you the game. For example, grim reaper perementally reduces a card by 50 rendaring that card essentially useless. Point is, because mythics are so strong, you can't beat someone with one. Which suck