I have noticed some weeks ago one strange thing in Zul'farrak. When a group is looting shallow graves for epic drops Ring of Saviors, Ardent Custodian or Nigthblade, the Zul'Farrak Zombies and Zul'Farrak Dead Heros very often raise from there and they always target one guy. That might not be surprising, but the point is that they always target same guy, no matter if he opened the grave or not. So the guy might stand in the other corner of the grave place and zombies will still go on him! What I did was went to Zul'farrak with rouge (was priest at that time so I had to use some invisibility potions) and when we got at place we opened 1 grave. Cool! zombies went on me. With no problems we killed them, than I mounted and rouge started to open as many graves as possible. Zombies started to chase me while I was heading to that bug area. After like 45 seconds I was dead and zombies started to attack rouge but he managed to open 3/4 of graves. Soon we have learned how to open all of the graves and not to die. So what you do is:
1. Group with one guy.
2. Go to Zul'farrak and stealth to the shallow graves.
3. Open one grave to check who the zombies target.
4. "Target" mount and run(remember not to run to far away or they will attack the opener)
5. Other guy shift+click on grave and than fast on another and another (he will loot everything you dont have to wait until info about loots is written).
6. Loot all graves than vanish/fagin death or just save your live and run to exit.
7. Reset instance and do it again!
8. If you got luck you should loot some epics.
We did it around 180 times and we got in total around 20 epics, 20 blues and some greens which were sold for more than 2400g (divided by 2 goes 1200+g to each one)and lots of junks that were sold for 300g. In total I made around 1400g. Later after some practice it took us 8 min for whole run.
PS: I still dont know who zombies will target, but suspect that they will attack guy who first entered the instance.