I see no problem with using magic in a duel. only you should not hide from someone if you are going to challenge them. I think that a duel should be fought with honor, and by that I mean that the big bullys should pick fights with other big bullys. Leave the new people alone so they have a chance to learn a little first.
Let the new people fight new people.
The dueling system is not right now and there are certain ones who are taking advantage of it. If you have honor, or want honor, you will wait until it is right, and even then you will fight someone of your own rank.
Spamming challenges while in a duel is not an honorable way to fight, it is a way to cheat, pure and simple.
Magic in a duel can be as honorable as swinging a sword, but your opponent should at least know where you are in the area. You should ask for a match first if you want to have honor in the win. A hearty \"good fight\" at the end of the duel will also bring honor.
But as there are many who wish to be evil, they (the evil ones) will see honor in anything they do, no matter what they have to do, just so they win and you lose. That is the way of every world.
I, myself, will only accept duels of honor.