Agree that we should not show levels. Let the players learn from their mistakes if they attempt to fight an Archdruid or Red Dragon or Beholder or Mind Flayer. I know there has been some concern that combat is hard, but that should be the case especially when dealing with these special chars.
Getting one shot from these characters should serve as a reminder that you can't just murderhobo everything even if you wanted to. This can also serve as a way to ensure the games integrity in a sense that important powerful NPCs really can only be dealt with via the Plot. Example taking out Kagha as level a group of level 2 instead of having the support of the Tieflings which results in heavy casualties.
