I think I may have found the best way to farm the lovely charms for some classes. If your class has a pet then you can go to the Halls of Lightning, go to where the slags are and just go afk in the middle of the room. The pet will kill them and you will still the charms for example im doing it with a 85 hunter in BM so I get spirit bond which always heals me so I never go below 90% health it also helps if your pet can AoE like the chimaera pet for hunters. Hope this helps some people in getting the mount or other achievements.