I'm stuck on this, too.  I had like 900 energy as a new player and was happily mowing along when this roadblock came up. Burned through pretty much all that energy till I realized it was hopeless.

Sure feels like a way to make me use all that free energy and try to hit the paywall sooner.  Hopefully it's just a bug cause I dig the game.

Their is not much that can be done about it except get used to frustration. Their are ones like that later on for 4 Star Items as well but those can at least be done on Hard or Brutal.

They are still frustrating but doing it on Brutal does at least mean you do not need a Top Tier Drop with a specefic primary stat so it goes faster due to being a middle grade drop.

My suggestion would be to skip those missions for now and then come back when you have heros strong enough that 1 or 2 can handle the entire level.

That way you can use the extra 2-3 slots not needed to complete the level as ways to build up Commons and Uncommons to be able to rank up better heros later on.

While it will not make the grind much less frustrating. You will at least be using energy for more then just getting frustrated at not getting the drop you want.

thanks Dragen3, it is actually what I'm doing: farming the stage for leveling up other heroes

no hints, then.

Finally completed this quest im lvl41 :P