And that is whay i said you need patience and perseverance in this game, eventually you will get good heroes, be it from gems, atlantis coins, tokens (didn´t forget this time), because chances are not cummulative, 100 summons equal to 100x 1.3% shots, not 100% of chance of getting one.
Big spenders do not buy increased chances, just more shots, if you still doubt it, look at this guy: Over 800€ invested in the game. And do not get a month's hero