For all the details on the new Codex Arena go to http://www.guildwars.com/gameplay/pvp/pvp_types/codex_arena.php then visit the Great Temple of Baltazar and give it try. All of the skills available for sealed deck play are listed at http://wiki.guildwars.com/wiki/Codex_Arena on the official wiki. Plus a new Codex Title has been created to track your progress.