Completely unbalanced and pay to win. Heroes are drawn randomly, but about 20 are over powered. Meaning that you almost can't progress in any modes in the game without them, and cannot beat a pvp mode against them without yourself having them. Unless you want to play for years, you will not be able to randomly get the best heroes by shear luck (the chance to get a 5 star is 1% and you have to get these 20 5 times each to max them out which will take a minimum of 10,000 summons)