Hela's difficulty level is too high
There needs to be a lower limit on how much Hela can regenerate and block damage in the Gods of the Arena contest.  I just fought her at the Heroic level, and I lost my entire team (including reviving one champion 3 times).  The final opponent shouldn't keep getting that much stamina back - when Hela's meter comes back from nothing 5+ times, that's too much.  I know it's supposed to be difficult, but that's ridiculous.  It takes all the fun out of playing, and goes from challenging to extremely frustrating.  I still have to play "Show of Force" three more times to reach 100% completion, but it's not worth it if it's that difficult.