General Info Vaelastraz the corrup is the 2nd boss in Blackwing Lair right after Razorgore the Untamed. Before the fight, Vaelastraz is sound asleep and everyone can roam freely in the room. The fight is started by talking to him. After a brief cut-scene the fight begins. Vaelastraz will now stay awake for exactly 60 minutes before he dies and despawns for 12 hours. While he is awake it is no longer possible to roam freely. Vael will attack anyone within 20 yds of his "middle". Since he's huge and ranged cant be made out accurately, as a general rule the raid should stay outside the inner "courtyard marked by the columns.
Abilities Everyone in the room will receive this buff when the fight starts:
Essence of Rend
Restores 500 mana per second.
Restores 50 energy per second.
Generates 20 rage per second.
3 minutes remaining
Random ranged members of the raid as well as Vael's main target will get:
Burning Adrenaline
Damage done increased by 100%.
Attack speed increased by 100%.
Reduces max. health by 5% every second. --> down to 18% after 20 sec.
Deals 4375 to 5625 damge to nearby allies upon death.
20 seconds remaining.
Fire breath:
AoE fire that hits everyone in an approximately 90° arc in front of him for ??-?? fire damage.
Cleave:
AoE physical that hits everyone in front of him for 1500-3000 physical damage.
Tailwipe:
AoE knockback that hits for 500-700 physical damage. Hits everyone in an 90° arc to the back of Vael.
Aura:
Damage aura that hits everyone for 300-700 fire damage per tick.
Burning Adrenaline BA is lethal. We use a mod to announce the burning one of his buff/debuff, so he can action accordingly --> run away from your allies (min 30yd) and resume DPS (which is largely increased). DPS only for ranged classes of course. If the MT has BA he turns Vael slightly to the right in order to make room for MT2, then dies in that spot. More on that later.
Frontal damage/MTs We need to work something out to prevent Vael's fre breath from killing the dps (just like onyxia)... now if they MT could be kept alive this would be no problem. However we have to feed up to 6 tanks to Vael before he dies.
The whole idea here is to make it impossible for vael to face the DPS by placing the 6 most hated chars (warriors) into strategic positions that direct his flame breath away from the DPS if a Tank dies and another one has to take over.

Vael has 3 limited AoE and 1 Aura type damage abilities. The damage zones are shown in the picture above. Note that he has a blind angle just over his rear legs.
Pulling Vael is done by one warrior that runs through him from the wall opposite the throne. By that he turns him and makes sure he doesnt move. 5 seconds afer initial aggro the offtanks move in and fight for aggro. 10 seconds after initial aggro all dps begins.
Positions during the battle are as shown above with raid entirely in the blind angle. All tanks are on one side. When Vael is at 20% Warriors activate Recklessness and Execute for maximum damage. At 10% all Rogues and Hunters stop DPS for 10 seconds. Rogues use feint and vanish whenever available. If it is resisted they stop all backstabs until they can cast a successful feint again. Hunters have to be carefull with dps after a good aimed shot crit. Feign death whenever available is mandatory.
If a ranged char gets BA, he will immediately run away from his allies to one of the green zones (around the columns). Once he arrives there and is still alive he resumes DPS which is greatly increased. If possible he stays clear of Vaels Flame breath and within 40yd of a priest, but never at the expense of safety for the raid.
When the current Main Tank gets burning adrenaline he stays in position. The offtanks get ready to get aggro and immediately turn vael back to the tank positions. During the transition vael must not move. So it is important for tanks to always stay within melee range of vael. Occationally on the transition healers might get a tailwipe and a short gap in the MT healing occurs. To bridge that we have 2 priests flashhealing the MT.
Note: An observation in regard to Vaels flame breath was, that he only does it when his target is stationary. So should you ever see yourself targetted by Vael, start to strafe right away in order to turn Vael away from your allies.
Healing Everyone takes damage, so the best solution is Prayer of Healing, which means 8 priests, one fore each group. If less than 8 are available, use druids with chaining renew+regrowth on all of their partymembers. But the easiers setup is 8 priests.
Then setup 2 druids or 2 more priests + 1 Paladin to chain heals exclusively on the current Tank so that at all time he has 1x PoH, 1x HL and 2x HT incoming on him. All priests who PoH, will also occationaly send a Flash Heal to the MT.
Buffs 5 Warriors will be dedicated tanks and buffed as usual. The surplus tanks will get BoS and join rogues for DPS. All other DPS will get BoS too as well as all healers. Rogues do not get Blessing of Might (to limit their DPS and crits so tanks can keep up) --> Essence of rend buffs damage, but not taunt/sunder armor.