Hooray, we just killed Illidan! We've been working hard to knock down the T6 raids before the expansion comes out (or for me at least, before the 3.0 patch). And on our third night of serious attempts we got him. We win BC! (Well, pre-Sunwell at least).
Illidan takes four tanks: a Warrior or Paladin for the emo elf, two fire resist tanks for the spawned Flames of Azzinoth, and a Warlock tank for the demon phase. My role was tanking kill target #1 for the Flame; a good choice for bear threat. Tanking it requires two things: the right gear and the right kite path.
Gear is straightforward. You need to be at full 365 fire resist with buffs, which assuming a Flask and a Paladin aura requires 260 in your gear. You get 200 of that from the Inferno Hardened Badge of Justice gear (100 badges total). Lots of ways to get the other 60: I use the Amulet of the Torn-Heart and the Phoenix-Fire Band along with +15 FR to cloak enchant. The Wyrmcultist's Cloak is another choice. Once you've reached 260 FR you also need to get to the full level 73 defense/resilience cap to be crit immune. For me that means lots of PvP gear. Beyond that, the rest of your gear should be avoidance. Armor is useless for the flames so you want stamina and dodge/miss, the more the better. So bring your Staff of the Forest Lord (or Wildfury Greatstaff if you can't), your Pocketwatch, Pepe's Shroud if you have it. I was at around 32% dodge and 17k health unbuffed on our kill. Sadly in all this FR gear your cat DPS will be poor (about 600 for me), but you're doing the hardest job in the fight so you need it.
The reason flame tanking is so hard is you're kiting through two kinds of fire while avoiding eye beams. The main thing is to keep the elemental faced away and do your best to stay out of green and blue fire. And if an eye beam comes lancing down, get the hell out of the way. Beyond that, in addition there's an invisible leashing mechanic where you and your fellow tank both need to be in 40 or so yards of the other elemental or it charges and wipes the raid. This part is invisible and confusing, so read the strats for positioning and be sure to move in tandem with your other tank. For me, this leashing was the hardest thing to learn.
On our successful kill I had terrible luck, got three eye beams on my side. The first actually hit me but I was one Crawdad away from dying so survived it thanks to my amazing healers. The third one also hit me just as my elemental was dying, that one did me in. Disappointing, but I'd done my job.
Just as I died our raid leader said "Flyv is dead; that's OK, he's not important for the rest of the fight". Which made me wince ruefully but he was totally right. If your an FR tank your gear makes you pretty weak. And positioning is really tight in this fight, so often it's better for you to stay out of the way than to try to add another half a person's DPS. In general fighting Illidan I find I'm most useful hanging out in the back and healing or else contributing some DPS to get down the demons in phase 4.
The whole Illidan fight is quite epic, a fitting challenge to cap a long and well designed raid instance. I'm very proud of our guild for stepping up to this challenge and getting him down.