This is a very simple feature to unlock and it will unlock the Insurextion arena which is Smackdown Card 11. Turn down Vince for the Tag Titles, talk trash on the mic, in roaming, go down the stairs and go towards the snack machines where Michael Cole is. Talk to him and say you were just kidding, win the battle royal, talk to Hebert instead of choosing to go after the hard-core title. Then you will go to Regal's office - take the shot at the European title, win the match and the match that follows and you have the new arena.