I did a quick search and didn't come across this, but if its already been put out there, then my apologies.
Now, we all remember the Reckoning exploit and the tons of fun we all had with that.
This is similar.
In Hyjal, Malfurion Stormrage gives you a quest, after doing a couple pre-reqs, to use the Flameseer's Staff on Baron Geddon to weaken him. Using the staff channels a spell on Baron and after 20 ticks, you complete the quest and can turn it in.
Here's the catch. At #20, Baron casts Living Bomb on you, which after 12 seconds explodes and does moderate damage and pops you up into the air. It also does the same thing to anybody near you.
I was unable to test if it stayed through a summon, as my guild had no warlocks on and trade wasnt very helpful. But I do know that you can hearth and the bomb stays with you.
Another nice thing is after you hearth, the bomb timer seems to stick, and you get a good 5-10 seconds before it goes off. I was able to run from the Inn to the AH and stand right in the middle before it exploded.
Then, just drop the quest and pick it up again, rinse, repeat. Baron isnt far from the quest giver and you dont really have to interact with any other mobs for it so its pretty quick if you get some people summoning you back and forth.
The Return of Baron Geddon - Quest - World of Warcraft Link to the quest. It shows horde on wowhead, but it works for both factions.
Enjoy