'each opponent' means that Chandra can be a great EDH card
You can't control the cards you draw, which is why it's so important to focus on making good choices with your opening hand
Obviously, I didnt get the chance to cover every single deck archetype out there, but this should serve as a good introduction to the most popular ones
Right now, this card is selling for a price which is impressive even by the standards of other mega TCGs like Pokemon
Those are the 15 cards I choose to play that let me go off with Nadu, and Im generally looking to have at least one of them or a way to find one of them in any opening hand, though its not strictly required if the hand is otherwise broken (such as any hand with Rhystic Study, a blue land, and Mana Crypt)
Secondly, it gives a power boost, so you can kill out of nowhere faster or with a 9-power dork that doesn't have infect at all