In our ten-man guild, we burn Onyxia with Heroism, no crackle in phase 1.

This is due to the fact that we have the adds tanked by Onyxia’s tank under cds as we can’t afford losing time on cc’ing the adds and have them off-tanked by a plate dps risking his life, assisted by a mage, losing in the meantime 2 dpsers to cc.

That means we begin phase 3 with Nefarian aroud 95%, depending on how much ranged damaged him in phase 2.

The kitter have to be really good, he needs to really understand how the shadow bolts works and have the timers with a bossmod. The phase 3 is looong. But after all, if your kitter can hold for 6-7 minutes, he should be able to hold another minute.

We grabbed first kill server with this method two weeks ago. The other guilds working on it on 10s and 25s for longer still haven’t killed him.

About the resist trinket, only tanks have it in the guild. We ask people to use their personal cooldown first crackle, then a bublle, then a dk bubble, then raid wall, etc… But I don’t know how different this is in 25s.

And be sure your raiders with short cds use them. My healers always know when I forget to raptor strike a crackle (6sec cd on the raptor strike – hunter ability).

People on the forums comment that Levitate can cause Ony to decide that someone is un-targetable, so she picks new targets.

http://us.battle.net/wow/en/forum/topic/2267599178#17
http://us.battle.net/wow/en/forum/topic/2089199945#4

#3, most guilds will put everyone on ony to start and bring her to ~10% then all switch to nef – switching back to nuke ony before her bar fills (normally pulling off 2 crackles this way)

#6, the trinket becomes more valuable in p3 when mana is lower and cooldowns are spent. it’s definitely valuable while progressing on the fight, albeit not required. it’s particularly helpful for classes like shamans who don’t have a personal defensive cooldown to use.

#7, you aren’t complicating it. the person with cinders will need a decent amount of healing but so will everyone else. overlapping is a really bad thing here. better to be well prepared than ill prepared. we even keep a hybrid healer (ele sham/moonkin/shadow priest) on each pillar to help out when a healer gets cinders.

sorry i skipped a few, but i don’t have much experience with those that i did and i didn’t want to give you any guesses.

Good luck!