In case this simple idea has slipped your mind or if ya didn't happen to consider, I just wanted to share a neat trick to quickly get whatever item you want to farm. I am on a high pop server so camping the oracle was just out of the question for the pvp shell. I went back 5-6 pages and didn't see anything related, so hopefully not a recent repost.
Download Oqueue and Waitlist for a bunch of RBG groups or Raids. Try to find a group that just started, and isn't nearly full yet.
Make sure before you get an invite you are at your camp spot (for me it was the island where the Oracle spawns).
As the raid leader invites more and more people, you will likely be changing servers due to CRZ. I killed the Oracle 5 times while waiting in an RBG group and got turtle shell on my 5th kill. You have to be quick with burst DPS though b/c you might phase out and not be able to loot corpse if someone else is invited.
Good luck!