Vaelastrasz:
Vaelastrasz is an intense, time-critical encounter. It must be completed while Essence of the Red is active. Essence of the Red gives casters 500 mana per second, rogues 50 energy per second, and warriors 20 rage per second. While it is active, mana, energy and rage conservation are non-issues, but it will wear off three minutes after the fight begins, and then healers will no longer be able to keep up with the damage being constantly dished out to the raid. Encounters with Vael are often described as "won at 2:45" or "wiped at 3:15".
Given the short time window, Vaelestrasz is most easily killed when the raid has tremendous DPS and adequate healing power. The encounter is a balancing act between threat control and DPS. It will test the raid's abilities on both counts.
For the first attempt, Vael will be lying on the floor, flagged as friendly. The encounter will begin when the puller (the first main tank) talks to Vael. Should the raid wipe, Vael will be positioned in the middle of the room and the raid must stick to the walls when getting repositioned. In this case, the main tank should approach Vaelastrasz head-on to begin the encounter safely.
Positioning for Vael is critical because he has powerful raid-wiping attacks in both the front (cleave) and the rear (tail swipe). These are some suggestions:
1) Casters (warlocks, mages, and their healers) should be positioned on one side of Vaelastrasz, against the wall, clumped together. Hunters and the tanking line up should be positioned opposite the casters. Rogues will be meleeing Vael broadside, staying between front and hind legs to avoid the rear tail swipe knockback and the front cleave attack. Offtanks should be hacking away closer to Vael's front, around his shoulders, ready to move to the main tank's spot. To reduce healing strain, only the next warrior should move toward this position at a time, due to chaining cleaves. The rest should be in a similar position as the rogues.
2) Ranged DPS and healers should stand against the wall to Vael's right. Melee DPS should be positioned at or just behind Vael's right shoulder (don't get too close to his front). Tanks should stand on the opposite side (Vael's left) near the rear leg. The off-tank should be positioned somewhere near Vael's left foreleg. The purpose of this positioning is to limit the damage that chain cleaves can do. The inevitable spreading-out that melee classes will do if they aren't careful can leave a lot of players vulnerable to chain cleaves, which will propagate from the main tank through the off-tank through the rogues. Every such chain cleave can kill several melee DPS players, and you simply can't afford those losses. If DPS players stay by the right foreleg, they will not be hit by a tail swipe when Vael rotates to his left to attack the OT.
Burning Adrenaline and MT Transitions
Every 15 seconds, Vaelastrasz inflicts a member of the raid with Burning Adrenaline. This debuff effectively turns its target into ticking AoE time bomb, who must move away from their group to avoid a wipe. Every third Burning Adrenaline will be targetted toward whoever is at the top of Vael's hate list (the main tank). All other BA's will be targeted toward random mana users in the raid. Rogues and Druids in feral cat form should not be affected by BA unless they gain aggro, in which case it is generally a guaranteed wipe.
When the main tank is afflicted with BA, the next tank on his hate list must move into his position and take over as the main tank with healing shifting over to the new tank after about 10 seconds, giving the BA-afflicted MT time to deal out some high-damage moves before dropping dead. If the next tank does not pick up aggro after the main tank dies, Vael will likely turn toward the side groups and wipe them out with his flame breath. When mana users are afflicted, they must move away from the raid. A good spot for casters is in the very back of the room, behind Vael's tail where they can unload a series of instant cast nukes before they die, helping to mitigate the loss of DPS.
Tips
During tank transitions, it is important for rogues to Vanish and for hunters to Feign Death. This helps ensure that they aren't above the tanking lineup on Vael's threat list. Mages, Warlocks and Priests generally do not have to worry about their DPS out-threatening the tanks; DPS warriors who gain too much threat can more readily move in to main tank, as can feral druids in bear form. When BA hits the main tank, the next tank in line should move to the tanking spot, spamming threat-generating moves to ensure that Vael focuses on him when the MT drops dead.
Throughout the fight, mages (hopefully with Arcane Subtlety) should chain-cast Arcane Missiles, rogues should continously Backstab and Feint, and other classes should keep as many DoT's on Vael as possible (Serpent Sting, Corruption, Shadow Word:Pain, etc.). Warlocks should have Curse of Shadows, Curse of Elements, and Curse of Recklessness on Vael at all times to bolster DPS. Priests must make sure to renew their Shadow Word: Pain between heals.
The main challenges in mastering Vael are having smooth tank transitions, having enough well-geared warriors to constitute the tanking lineup (4-5 is good), careful threat management from the rogues and hunters, having sufficient healing and having sufficient fire resistance on everyone. Mages and Warlocks aren't generally challenged in this fight since their mana is constantly replenished by Essence of the Red. Priests are likewise under no pressure to conserve mana, though they have to watch their timing as usual.
Rogues can do tremendous damage in this fight, especially those that are dagger-specced. Rogues are essentially set free by Essence of the Red. They can repeatedly backstab with little or no thought to their energy level. It is critical to use Feint as much as possible throughout the battle, however, and to use Vanish on the first transition or when the first MT gets BA. This will keep the rogue's threat relatively low so the second Warrior can hold aggro.
One technique that can prove useful is having a suitably geared druid in bear form as the first tank. As long as they are specced and equipped appropriately, they will have no aggro problems, and this keeps one more warrior alive to Execute when Vael's health drops below twenty percent.
Keys to the Fight
1. Keeping the MT up until Burning Adrenaline hits.
2. Keeping the OT topped off so they can survive the sudden burst of damage that will occur when Vael switches after the MT dies.
3. Keeping the tank order clear. It is critical that the healers know who is next so they can prepare heals, and the tanks need to know who is next so they can move into position.
4. Watch positioning, avoid chaining cleaves into the dps.