not an exploit really, but use it while you can.
Now that we can get the set items from Khadala a lot of people just want to get shards quick to gamble.
Make a low level game with another account and the clear it with your high level on T6.
Gives about 100 shards. I'm betting blizz will be putting a stop to this soon.
Get a group of people and take turns opening rifts