Once I tried out tto turn on the auto-accept option with some guys. We put it into our descriptions (OOCly) to show that we don't avoid fights. We hoped to get involved in more fights by doing this. The experiment failed. The reason is that you can't roleplay with auto-accept on. You have to watch your system messages continuously to avoid being attacked while you are typing.
Therefore, I propose a countdown which starts everytime a challenge begins (not only the auto-accept ones). Like this for example:
Duel with $target starts in 20 seconds...
Duel with $target starts in 19 seconds...
Duel with $target starts in 18 seconds...
...
Duel with $target starts in 1 second...
Duel begins!
This would give you enough time to prepare. It also will make the phrase 'Jump when you are ready' obsolete.
Also, a list with active duels would be helpful (when you have auto-accept turned on, and you are challenged by more than one player, you lose overview soon). Maybe you could use the group icons to show your current opponents. This would also be helpful in guild wars, if the online players of the enemy guild would automatically appear in the list. And of course it would also be helpful in PvP areas.
