Currently the only way to experiment different combination of hero's is to lvl up them, put different gear, and then try it on the game content, I feel there is another way to maximizing player to try different combo without the hazle of grinding countless time. The good example of this has been implemented on DnD campaign collaboration, so I highly suggest to apply such thing in practice mode too. I believe many player will really appreciate this.
#Add feature to LV max stat on hero's in practice mode.
graceful moat
gilded owl
If there is such a mode, i would like more customisation rather than the fix stats that DnD campaign collab gives (which is very bad for supports)