This has probably been suggested before but I'll throw my two cents worth in. I don't feel in the game that there is any reason to focus on building up characters that you never use. I have all the heroes but on several of them I haven't invested any time or effort in putting runes or even paying out their abilities to full power. So this is my suggestion. A new game mode where your team is randomly selected from all your heroes. Your team then battles a relatively low level team just in the tower. If you win then you get a little reward and you move onto the next team to go up against and an increased reward. Your team is either swapped out for a new bunch of random heroes or you are forced to keep the same team for the progress through the battles. If you lose then it's basically event over for you for the day. I think this would encourage players to push every hero to full stats and gear and open up players to unique synergies that they may not have encountered. You might get lucky with a random team of good heroes but at some point your weakest link is going to be your weakest heroes.