Well, I know that many people have come across lots of trouble on the last boss, Ley-Guardian Eregos. I also know that the achievements are pretty difficult. Now my guild and i have been doing this boss on ez mode while getting an achievement!
Group Set Up:
Red Drake x2
Green Drake x3
With this you can not timestop the boss, but with three healers it is easy!
So you have 1 red MT and 1 red Burn the boss and the whelps. The 3 greens should apply their poison on the boss. Then channel their heal and keep the tank up. Have the OT red drake store combo points just incase the MT gets low on hp. If he does, have the OT pop martyr and evasion. With this have the healers heal the MT and keep the OT up till the MT takes over. When the Purple Orbs spawn, just fly away going around the base of his platform.
With Whelps going down very easily and the boss consistantly being burned, this fight becomes easy! In the end you get Amber Void - Achievement - World of Warcraft !
Have fun downing the most annoying heroic boss !