Mmk its not really an exploit but its kind of useful for warlocks, if your in an instance and need to repair or grab something at your hearths location, you can summon yourself, have your party click the portal, hearth, do what you need to do (repair or whatever) and accept your summon and it will port you right back into the instance where your portal was. Really useful if your doing MgT and need to repair.
Dunno how long it will be before blizzard nerfs this or if they will at all.
And sorry if its a repost, went through the last 8 pages and didn't see anything.