The essence of the tactics when playing as the Dark Elves.

Well, each player decides this for themselves. And many factors influence the battle tactics. For example: hero development, obstacles on the terrain, the opponent's faction, elemental matchups, and even the landscape where the battle takes place, and much more. P.S.: Personally, I don't like it when I'm given hints during a battle (it has happened). But in general, you answered your own question... IMHO.