Now that we have costumes which allows those heroes to have 2 sets of heroes per (lets say) playing card.
Why not create a Quest or raid like battle which involves using both the standard hero and it’s custumed friend.
Lets presume all 5 heroes have costumes on both sides in the battle then you would do battle as usual with the standard hero but once the standard hero dies his costumed friend comes to life and the battle isn’t over till all 10 heroes are killed.
This would most certainly make an interesting long lasting battle.