Well folks, in Grizzly Hills there is a quest where you have to escort Harrison Jones to safety. Before he runs to the exit, he enters a ceremonial chamber, frees some chicks and then a giant elite snake appears. Now, this snake spawns many trolls with about 1.5k hp all the time depending on your level of course.
The Exploit:
These trolls die in 2-3 hits since they got so low hp, but they give the same xp as any normal mob with the usual 10-12k. This allows you to grind xp quite fast. Of course you shouldn't dps the snake cause if he dies, you gotta reset the quest.
Just let Harrison jones fight the snake while you do the adds. After a while, Harrison will die, but you can just retake quest and do it all over (doesn't take all too long to get to the snake part again). If you have some kind of heal or dispell you can help Harrison a bit by healing/dispelling him to make the fight last longer which in return means more exp for you.
The actual quest: Dun-da-Dun-tah!
The NPC: Harrison Jones
The mobs you should kill all the time: Ancient Drakkari King