While offensive flashy spells are often used in dueling and have their place and defensive spells can help to protect oneself during a duel, I believe that the best action is to cast a spell that hinders a person’s ability to think straight. In this case I would argue that the usage of confundo would be the best offensive spell to use in such a case as dueling. It not only is an offensive spell, but hinders the need of defensive spells that would not help you win a duel. It instead confuses the opponent to the point where they are no longer able to think straight about the best way to win and thus gives you the perfect opportunity to win a duel.

I believe that a disarming spell is the most effective spell to use while dueling. This prevents the opponent from being able to cast a spell, effectively protecting yourself in a duel as well as earning you the points needed to win a duel. Simply evading your opponent’s spell only gets you so far in a duel before you must go on the offensive, thus a disarming spell is a good balance of both defensive and offensive.

To win a duel I believe you need to be ready for anything. In this case I would say that a levitation spell, wingardium leviosa, would be an excellent spell to use in a duel. This spell would allow you to dangle your opponent, or their wand, in the air, thus preventing a spell from being cast in the proper direction (or at all).