Hope this can help our future raids...
from the easier to the harder, taken from wowwiki
Arachnid QuarterA web-covered wing of Spiders and Cultists of the Cult of the Damned. Three bosses. This is the entry level quarter, usually the first one targeted by guilds to gear up their players. The trash clear to Anub'Rekhan is short, with the clears to Grand Widow Faerlina and Maexxna being progressively longer.
Anub'Rekhan is the first boss of the Arachnid Quarter in Naxxramas.
Commander Eligor Dawnbringer: "Anub'Rekhan, one of the finest Spider Lords of Azjol'Nerub, was brought under control of the Scourge when he and his commander, Anub'Arak, were finally defeated by the Lich King many years ago. It is said he was the most loyal of Anub'Arak's commanders."
In the book "On Naxxramas", a low-level member of the Scourge finds himself distressed by "the perverse nerubian..." always calling with invitations to its "parlor."
10-man Abilities * Anub'Rekhan has approximately 2,230,000 hit points.
Anub'Rekhan Impale: This is an area-of-effect ability that targets a random player and hits everyone in a straight line between Anub'Rekhan and the player, causing 4813 to 6187 physical damage and launching the affected players high in the air, who then suffer 50% fall damage when they hit the ground.
Locust Swarm: Every 70-120 seconds, Anub'Rekhan slows to 60% normal run speed and casts a spell that causes AoE damage in a 30-yard radius around him that centers around him as he moves. Remaining in the radius of effect causes a DoT debuff of 875 to 1125 nature damage every 2 seconds that stacks repeatedly, and which silences those afflicted. When he casts this spell, another Crypt Guard also spawns at his initial engage point. Lasts 16 seconds.
Notes:The Locust Swarm attack has an approximately 90-second cooldown, but the first cast may occur between 80 seconds and 2 minutes. Its silencing ability is unlike a normal silence, as it prevents the use of all abilities, even auto-attack. This means that the main tank cannot use Shield Wall or Last Stand to save himself if he gets stacked too high. Items, however, may still be used.
Aspect of the Pack can be used to get out of the Locust Swarm range but requires timing and coordination from the Main Tank and Hunter. Unholy Aura will also work if the Death knight stands a little further ahead of the kiting path and runs with the Main Tank to the initial tanking position. If you are late on your kiting and start stacking up the debuff, drink a swiftness potion.
Summon Corpse Scarabs: Whenever there is a corpse in the room (either a player or a Crypt Guard) Anub'Rekhan can spawn corpse scarabs from it. This is not on a set timer. Ten will be spawned from a Crypt Guard and Five from a player. They spawn with threat on random players and will spread out and attack random targets.
Crypt GuardsOne of these adds spawns after every Locust Swarm. In addition, one spawns approximately 20 seconds after Anub'Rekhan is pulled. They have around 234,000 health. They have a cleave, a stacking acid spit DoT that ticks for 500 a stack, and a low-hp frenzy that increases damage by 50% and attack speed by 60%.
StrategyThe fight layout, with optional use hunter.
Although doable with two tanks, three tanks are ideal for this encounter. One of them should tank Anub'Rekhan, while the others tank the Crypt Guard adds and the Scarabs that spawn from their corpses. In the 10-man encounter, the two Crypt Guards are not present at the start of the fight, making the third tank unnecessary. A hunter is helpful but unnecessary.
The main tank engages Anub'Rekhan and drags him back to where he was standing originally (note that tanking him against the wall can cause evade bugs should the tank be impaled). In the 25-man fight, the other tanks pick up their Crypt Guards while the DPS focus them down. These should be tanked and killed relatively close to Anub'Rekhan. Due to the acid DoT the Crypt Guards apply infinitely these should be killed quickly.
After this, the raid should spread out in a semi-circle around Anub'Rekhan to minimize the effects of impale. Mages should be ready near the Crypt Guard corpses to frost nova the Corpse Scarabs as they come out; the offtanks should be on or near these corpses to pick them up. Ranged DPS should focus and kill the scarabs before returning to Anub'Rekhan. You should have a decent amount of time to DPS Anub'Rekhan before the first Locust Swarm. One player—ideally a Hunter—and a healer stand 30 yards from the main tank on the edge of the room past the ring of slime. When Locust Swarm is cast, all players must immediately run from Anub'Rekhan to the other side of the room and remain more than 30 yards from him for the next 20 seconds.
The main tank, when he sees the Locust Swarm cast bar, must begin kiting Anub'Rekhan along the edge of the slime to the other side of the room. The hunter should have Aspect of the Pack on. The healer should move with them and avoid getting any stacks of Locust Swarm in order to be able to heal the tank and hunter should they be hit. A warrior tank should use Intervene to gain additional distance. Locust Swarm ends when Anub'Rekhan reaches the other side of the room, where he should be tanked as before, with the raid spreading out in a half circle. Another Crypt Guard spawns during this time; pick up and kill it. Again, Mages should be to be aware of Corpse Scarabs spawning from it. After this, the encounter continues, with Locust Swarms coming every ~90 seconds until Anub'Rekhan is dead.
Alternate strategy (10 man version)The kiting strategy can be difficult to master for a group with poor coordination. Ranged DPS might get caught in the swarm trying to kill the adds when the tank kites, and cause everything to go wrong. An alternative strategy is to not kite at all, but have the tank stay put and take the full damage of the swarm while the healers spam heals on him. This is entirely possible and will make the fight more of a tank-and-spank with extra healing on the swarm. Death Knights are good tanks for this tactic because they can time their damage reduction ability with the swarm and take less damage. Using Anti-Magic Shell just before Locust Swarm is cast will make you immune to the swarm for 5 seconds (7 if you have the glyph). Tanks simply have to make sure that they use their damage reduction ability before the swarm because it silences them.
Once you enter the area where Anub'Rekhan is located, have a hunter misdirect (if available) onto the main tank and pull the boss to the actual entrance doorway area and tank it there while the rest of the raid runs forward and splits into a semi-circle roughly in the center of the room. Have your secondary tank behind everyone, where the adds spawn. All ranged DPS should spread around to avoid the impale. The offtank can add some DPS or even some off-healing to the party, but be ready to pick up the adds that spawn in the back, as they can easily one-shot a cloth wearer. Once the add spawns and the offtank picks it up, all the DPS has to do is simply turn around and burn it down. Do the same when the Corpse Scarabs spawn. This tactic is meant to reduce any kind of confusion in the kiting method, so separating the boss and the add makes the fight really simple. Remember that this method only really work if your healers keep the main tank topped up, especially during the locust swarm. Due to the massive damage that tanks take from the end of a Locust Swarm, any off-healers—such as shamans or paladins—should assist in keeping the main tank alive during this phase.
Note: The adds do not hit the offtank really hard, but with a low-DPS group the damage debuff can stack and be really painful. A nice way to prevent extra damage is to stun, as this prevents them from casting the debuffs at all; these debuffs last for 10 seconds and are reapplied every 2 seconds, so if you can cast a stun (such as Hammer of Justice) when your tank has 8 seconds left on the debuff, and add one more at 2 seconds, the debuff will start to 0 again, largely reducing the damage taken. The goal is to have a chain stun ready when the elite is around 50% health to reduce the overall damage taken. The adds are undead, so the paladin undead AoE stun can work for 1 sec.
Extra Note: The small adds that spawn from the corpse are really fast and can get out of a consecrate.
