Arch note I'd consider the most impt:
Doomfire will pick a target, follow that person, then randomly switch to another person. It will usually switch to someone close to that person, and if no one is near the last kiter/target, it will switch to some random person who might be on the other side of the field and the fire will loop around everywhere =P
We used the 5 group strat, 4 groups separated, melee group behind arch (take care not to be close to tank or tank might get airbursted when melee get it). If you get doomfire, turn 180 degrees and run in a straight line away from arch. Don't strafe, don't stop running away until that line of fire has stopped moving. Most mistakes happen with seeing the fire next to you following another person, and not moving, or running away, then seeing the fire transfer to another person, you run back to position, in which case the fire will probably transfer to you again and you've now looped it back to the raid.
This fight is about movement, falling damage nublets, decursing, and keeping yourself alive.
Mages should never die in this fight, ours were just blinking to the ground >< Undead priests will never get feared in this fight (between wotf, pvp trinket, and fear ward) so they can cover the tank with hots once the fear timer is up, and during fear they have to tank heal.
Levitate and feather fall is nice, but keep in mind, if you are burning to doomfire, or decursing was slow and you still have a curse while airbursted, the damage will break your levitate, and you will die from the fall damage. Just practice with the tears, then augment it with your levitate/feather fall.
Holler if you have any questions, and good luck