They have 29k HP always had that much. They also move really really really slow. If you get agro then kite :P
I keep telling to people that i get to group with to have the nameplate visible for that fight, and if they see that the ghosts getting close to you you simply run a bit. The group damage is next to nothing if everyone just move from bad stuff anyway, and the big add don't hit the tank that hard.
well i use demonology... all players are sticking pretty much together, therefore all spirits are in range for AE... and if there are too many, i use pet blade storm and hellfire, if there are too many a second time I pop infernal, and by the third time bladestorm is ready again, and if this happens a 4th time something went very wrong... lately no problems with Jindo...
As Demo/afflic I just felflame till I get aggro then dot them up. Macro your pet to felflame too, putting it on defensive will end up with your pet on a berserker or something. Put a port near an unbroken chain and run around.
As destro I just single target nuke. When conflag is off cd I kill one with immolate+conflag, then nuke the others with incinerates and repeat. BoH broken chains.
Honestly, preference of spec for that fight would have to be destro. Killing them is a bit easier with incinerate being such a short cast time.