Arena dueling is where you duel other peope in the "arena" to either gain or lose MSA points.
What is an arena duel?
An arena duel is the best of three match the winner must post a screenshot and then post it in the arena section of the forum. Then either the opponent or a watcher must confirm it, then the appropriate points will be won/lost.
How many points do i win/lose?
Well for getting a win you gain 10 MSA points.
But if you lose you lose 5 MSA points.
You can also bet a certain amount of points to change the regular 10 for win and 5 for losing