Must continue to buy shards to get a legendary character. Even when they say that they have increased the drop chances, it still doesn't increase. I've opened 10 Legendary Crystal's and almost 100 Void and Ancient. I have received several Epic characters, but no Legendary. The latest con is that you'll get a 50% chance to open an Epic or Legendary character if you spend $30. Nope. 

Beware of trying to move up in this game. Continue at the cost of your wallet.