"Free Balance Refill" event.
It opens with tab “Return”
During the event, you can get a reward by buying a certain amount of Gold in one day.
The more Gold you buy the better reward you get.
If you buy 20000 Gold, for example, you’ll get not only Chest of Talent Card Sets, Rune Box, Dimes and Thematic Event Medals, but all previous rewards too, which is a lot.
Every day at 00:00, your event progress and reward progress are reset. So every day you have the opportunity to begin again and receive all these amazing rewards, which increase your hero’s characteristics and you have better chances to be the top player.
So you’d better hurry!