Be warned! Every time you enter Cave of Prophecy, it counts towards your daily 10.
So, If you leave to get 21:52 Heaven's Voice: You have received the Invasion! Quest., then go back, you've lost an instance chance. Already finding a few people asking why they can't get in. Check in your Battlegrounds tab - Instances - and make sure you have some left before you leave. You get a new point only every couple hours, so don't waste them!

Admin, Please change this the way you did Shaab. This is uncool to limit the play time of the few players you have left.