The most powerful warrior.

actually, the strongest ones are the new archers (if they aren't approached and generally not noticed), 7 archers can take down 7 level 7 units one by one.

What new archers are you talking about? If you mean invisibility, it disappears after three turns or when someone approaches them! And besides, those aren't archers! There are no invisible archers! Stalker and Night Queens are just regular warriors! And the strongest and most useful are still Dragons! All of them!:)