Ok,first of all this only works on retail because on privates,illidan doesnt use skills except fighting with his warglaives.So to get it started:
Raid setup:
1-Main Tank
2-Fire resist Tanks(365)
1-Warlock SR Tank (250)
7-8 Healers
13-14 Dps
Illidan has 5 Phases,25 minute hard enrage timer.
Phase One:100% to 65%
Hits on 6-8k on Plate
Shear:This reduces the MT's health by 60%,Shield Block MUST be used to stop it.
Flame Crash:Illidan flies into the air for a second the lands creating a fire patch with a 10 Yard Radius,5k Dmg a sec.
The Tank must move Illidan away from the Fire
Parasitic Shadowfiend:Illidan casts this debuff on a random raid member doing 15k Shadow Damage over 10 Seconds.Once this debuff is complete,2 Parasites Spawn with 6k Health and target a Raid Member.If the Parasites reach the raid member,they get the debuff causing 15k Shadow Dmg over 10 secs and another 2 Parasites spawn.When Illidan casts Parasitic Shadow Fiends,the target runs from the raid and Frost Mages and Hunters kill the Parasites.
Draw Souls:A frontal cone of Shadow Damage causing 5k Damage and Healing Illidan for 100k.Just continue healing and DPS him down to 65%
Phase Two
Illidan flies into the air and throws his Warglaives into the ground,on both sides of the circular grate.Two Flames of Azzinoth will spawn,each with 1.1 Million HP.They both need to be killed to progress to Phase 3.
The raid needs to split into 4 groups around the inside of the circular grate to avoid too much splash damage from Illidan.The fire resistance Tanks will pick up 2 Flames of Azzinoth,if anyone is 30 Yards or more from the Flames they will Charge.The Charge will cause the Flames to Enrage,wiping the raid.Thus everyone needs to be on the grate.Each Tank must have 2 dedicated healers.The Flames also cast Cone of fire to appear on the ground,the tanks must move from the fire.Illidan will continue to attack the raid using several abilities while in the air.
Fireball-Fireball will randomly be fired all around the grate area non-stop.They hit for 3k and splash for 10 yards.
Have your Shamans pop Bloodlust and spam Chain Heal the raid.
Eye Beam-Illidan will cast a large blue beam that will usually cross the outter rim of the grate,tanks must avoid it.
Dark Barrage-Will target a random raid member and Barrage them for 30k Shadow Damage over 10 seconds.Make sure the target is immediately spammed with flash heals.
Occurs fairly rarely and randomly generally over 2 minutes once Phase 2 has started.
Kill both adds,heal like crazy and phase 3 will start.
Phase 3(Lasts 60 Seconds)
Illidan will use all the same abilities as he did in Phase 1,Agonizing Flames.
Agonizing Flames-Initally hits a target for 4k Fire Damage and then deals increasing fire damage over 1 minute.Agonizing Flames has a 5 yard Splash effect.Everyone MUST spread out.
Continue to Dps,kill the Parasites,heal and stay spread out.After 60 secononds,Phase 4 begins.
Phase 4 (30 Seconds)
Illidan kneels down and transforms into a demon.This is an aggro reset.At this point,the Shadow Resist Warlock Tank must move into position and spam searing pain to pick up Illidan.
Illidan hits for 500% more melee Damage in this phase,that is why is tanked by a Warlock.
Aura of Dread-A 15 yard Aura from Illidan causing 1000 Shadow Damage a second and giving a debuff causing more Shadow Damage.
All Melee Dps MUST stop and all Dpsers will move to the back of the terrace.
Shadow Blast-Illidan's main attack in Phase 4,hits for 8-11k depending on resistance.20 Yard Splash effect.Illidan will continue to spam this on the Warlock Tank,he must have several healers and must be away from the raid.
Flame Burst-Hits everyone in the raid for 3k Fire Damage,is used every 10 seconds and has a 5 yard Splash effect,SPREAD OUT!
Demon Within-15 sec into Phase 4,Illidan will spawn 4 Demons at this feet.They will randomly target 4 people.The targets of the demons will be stunned,the demons will move towards them and if they reach the target,they instantly die.The Demons have 22k HP and must be slowed and killed,but people must remain spread out.
Almost all Dps will stop during this phase as you kill Demons and you heal thought the Flame Burst.
After 30 Seconds,Illidan will switch back to Phase 3 and will switch back to Phase 4 after 60 seconds.He will continue to do this until 30%
Phase 5 30%-0%
During the beginning of Phase 5 everyone is stunned and Illidan ceases attacking.Maiev Shadowsong appears.Maiev and Illidan talk for 30 seconds then the fight begins again.Illidan will continue to transition between Phase 3 and 4.
Maiev Shadowsong will help Dps and spawn Traps around the map the can increase damage done to Illidan by 100%.
Unless your DPS is so low that you might not make the enrage timer,then ignore the traps.Also,after 30%,during the last 20 Seconds of Phase 3 Transition,Illidan will Soft Enrage,increasing his attack speed.
Heal the tank through the mini enrages and continue transitioning through Phase 3 and 4 until he dies.
GOOD LUCK!!