Secondary skills in Heroes 3.

I consider intelligence to be useless, just like ballistics. Before a battle, you need to calculate who will go first and use speed artifacts. The same goes for magic. Stock up on magic at wells or with an artifact. I prioritize heroes that provide resources and money above everything else (especially if a tower or castle gives the player +1 dragon stone per day), and then I send them somewhere, like to a Sanctuary, and they will be generating dragon stones throughout the game.