If you're planning to participate in World of Warcraft's Arena Tournament, then we have some important news for you. It'd be a good idea for you to get used to using the basic User Interface and select custom macros to get through the tournament, because Eyonix mentioned that you'll have to make do with the basics once the live event happens.

Here's the post we found from Eyonix on the Arena Tournament forums:

During the online phase of the tournament, there are no restrictions in regards to what add-ons players can use. For the live event, there are restrictions in place limiting players to the default UI and custom macros.

With an even playing field like that, you can be sure that only the most dedicated and skilled players will be able to get through the live events. For all those who signed up, we wish you the best of luck!