I have some videos of my group killing them in my sig.
Cho'gal, if you dont interrupt quick, you are going to fail. Your group need to be the quickiest possible. A frost DK/shaman/moonkin/hunter can interrupt that quickly. Adds, you will usually aim to go to phase 2 right after the 4th big add pop. After killing the first batch of adds on the second phase, make sure he isnt throwing fire and take him atop the stairs, so next batch of adds pop in the stairs, making it easier to interrupt them and possible to down them with AoE. Kill them quick, resume to Cho'gal.
Nef, we usually try to hit the 3rd Eletrocute right after Oni dies, so theres time to throw a Tranquility before the lava. People need to get out of lava quick and interrupt the small adds everytime. If your dps is too good, try to get nef down to around 63~62% before going to 3rd phase. 3rd phase, position everybody, get the Eletrocute, burn him as quick as possible. Tanks need to know how to kite him right. Since I never did it, only saw, Im not sure I know the perks of kiting the big adds. All I know is that Nef tank will sometimes have to rotate Nef and people dpsing will have to look out for fire patchs in the ground.
Good luck.
edit: Oh, first phase of Nef, have a decent frost DK that know how to kite things. Will make it a simpler fight.
Edited, May 28th 2011 4:58pm by Brisin