afk doesn't give much exp after the nerf, tagging mob gives more, bliz buff the mob exp..those boss mob gives more exp.

Well, actually this trick is not that great. I tested it a few rounds, it takes around 5-6 minutes to complete the whole cycle and it rewards about 5-6 bars of exp after level 90. If everyone has stayed and completes all the stage, and follow the big group to kill +2 elite mobs, everyone will have get more than 22 bars of exp, and it takes around 15-20 minutes depending on how fast everyone travels to the right elite. The key is to get into a big group though, otherwise you won't get that much exp.

However, due to more and more people knows about the trick mentioned above, the group that try to complete all stages now are usually left with not enough people to kill elite boss fast enough and it takes longer most of the time. So if really wants to get exp as fast as possible, best bet now is to use the above described method.