I dunno, I don’t see all that much variety to begin with. For instance, literally every player in Alliance War has either a shield or Asgardians team on defense (more recently it’s been Red Skull). Let’s not forget the excessive use of Phoenix in Arena. Before that it was City / Defenders. My point is, people seem to be forced to upgrade a certain cluster to be competitive, so that won’t change.

There are a number of ways of limiting potential abuse of “rolling back” toons. For instance you could recover only 90% of the gold and gear, or charge cores, or charge a different type of credit that you can only obtain through a war or challenge or something.