I feel like a Training Room/Arena would be helpful to test out team builds and hero ability/damage. I am aware that your can spar with another player’s team/heroes, but that only happen IF they post up their heroes on chat. There should be an option for players to make their own mock battles by creating an enemy team where they can tailor the level, power, and badges of the enemy team to test out their own teams. Even have an option to place in a training dummies with large HP pools so you can test out a hero’s damage output and skill performance.
I think this would give players a great planning tool, as well as an easy way to test out and find potential bugs in the game that the developers might have missed. Also would be a good way to test out and see if buffs can stack without the chaos of an actual battle.