
Note: Most of whats written here comes from wowwiki.com as its a good guide and entirely correct.
Abilities
Impale: Random target 10 yard AoE dealing 2500-3000 direct damage plus fall damage based on the maximum health of the player. Can be healed and mitigated by spreading out and using slow-fall abilities.
Corpse Scarabs: Whenever a raid member dies, several Scarabs (5-8) will spawn from their corpse. The scarabs are non-elite 60's with around 6000 health and can cause 200-300 damage a hit. With only one death, the scarabs are more of a nuisance, as they can be frost-nova'd and AoE'd fairly easily. Any more than 1-2 deaths will cause this to be a significant issue to the raid, and things will often spiral out of control very quickly if 2-3 people die at the same time. Corpse scarabs also spawn from the corpses of Anub'Rekhan's Crypt Guards.
Locust Swarm: Anub'rekhan casts a spell that causes AoE damage in a wide radius (30 yards) around him, he will also slow to 40% of normal run speed. Remaining in the radius of effect will cause a DoT debuff to stack repeatedly, dealing a large amount of damage, around 500 damage/sec per stack. When he casts this spell, a Crypt Guard will spawn at his initial engage point. Curse of Tongues will slow down this cast and is (extremely) important to surviving.
Crypt Guards:
- Cleave: ~1000 damage to melee.
Poison DoT: Stacking Posion DoT which stacks almost every attack, counter this by having a second tank taunting fairly often.
- AoE Net: Stops all movement for all those affected, it is important that melee get into position before the add does this attack.
- Explode: 10-15 seconds after they are killed, Anub'Rekhan can use an attack to explode their corpse, causing ~10 Scarab Beetles to spawn. Distance to Anub'Rekhan seems to be a factor to whether or not he will explode the corpse.
- Weakness: Can be stunned
Pull
Tanking Setup:
1 Warrior, 1 Hunter, and 3-4 healers for Anub'Rekhan
2 Warriors and 2-3 healers for left Crypt Guard
2 Warriors and 2-3 healers for right Crypt Guard
The rest of the healers will be designated for recently Impaled players.
There are two spots to tank Anub'Rekhan; where he stands when you engage him, or pulled back by a hunter to the entry-way of the room. After he is pulled into position, the MT should face Anub'Rekhan towards the East, the reasoning for this is explained in the next section.
The two Crypt Guards need to be tanked as close as possible to their initial postions, with them facing away from the DPS to avoid cleaves. Since they are very susceptable to stuns, rogues and warriors should be trying to keep him stun-locked in place while DPS takes them down first.
The left Guard should be taken out first, and his tank should not be getting more than 3-4 applications of the poison DoT. If he is, then the stuns need to better timed, or a second warrior needs to be taunting. Meanwhile, the two tanks for the right Guard should be bouncing aggro back and forth with taunts to avoid the DoT stacking too high. DPS finishes off the left Guard before coming over to kill the right the same way.
At this point the first corpse may have exploded into scarabs. If so, have Mages frost nova them into place before Warlocks/Mages AoE them down.
After the right Guard dies, you should be 60-75 seconds into the fight. Only ranged DPS can go onto Anub'Rekhan before the first kite. Melee should stand on the corpse, picking up scarabs if it explodes, they would only have about 10 seconds to do damage before they would need to back out for the Locust Swarm.
Process
The key to avoiding the Locust Swarm is to have the MT visually spot that attack occuring. The only cue to this attack is to watch Anub'rekhan lift his tail into the air, almost bowing at the MT. After the tail lift, the MT has about 2 seconds to get out of range before the DoT begins to be applied. There is no emote associated with this attack, only the visual cue.
The most important part of the fight is the kiting that needs to occur every ~90 seconds. Keep a timer going after each Locust Swarm cast.
As soon as Anub'Rekhan bows at the MT, signaling the beginning of Locust Swarm, the MT must immediately start running around the east side ring of the room, just beyond the poison slime ring. The MT should stop running when he reaches 12/6 O'Clock, depending on where you initially tanked him. Everyone else needs to back out of the 30 yard range of the Swarm, including MT healers.
As soon as the MT starts running, the Hunter in his group must also turn on Aspect of the Pack and run ahead of him around the same outer ring and turning off Aspect when the MT is in the 12/6 O'Clock position. If done properly, only 1-2 applications of Locust Swarm should be on the MT, just enough to be healed through.
Reaction time to the tail lift is crucial to surviving each kite, a 2 second delay will spell a wipe for the raid. It is also just as important that the tank avoid stepping into the slime ring, as it will put a debuff reducing all stats to 10% of normal, effectively dropping his max health by 5-6000 points.
At the same time the Locust Swarm is cast, a brand new Crypt Guard will spawn at Anub'Rekhan's inital engage point. This add should be pulled towards the western part of the room, to stay out of range of the Locust Swarm, and is killed identically to how the first two were brought down. After the newly spawned Guard is killed, all DPS can go back onto Anub'Rekhan, again, having 2 mages keep an eye out for scarabs. If done quickly and efficiently, this leaves 45 seconds of straight DPS on Anub'Rekhan before melee must back out and the next kite and spawn occurs.
80 seconds after each Locust Swarm cast, all melee DPS needs to back out of range and prepare for the next Crypt Guard spawn.
Rinse and repeat 4-6 times to bring Anub'Rekhan down.
Ramblings
Have 1 Priest and Druid cast PW:Shield, Renew, Regrowth, and Rejuvenation on the MT as soon as they see the tail go up in the air, this should provide enough healing for 1-2 Locust Swarms.
1-2 healers can be at the other end of the room, during the kite, to heal the MT if he got a few Locus Swarm stacks on him (shouldnt get any in the first place, but better safe than sorry).
Swiftness potions can be used on alternative kites for safety. Alternate kites because they are on a 2 minute cooldown, you cannot use them for every single swarm.
Detect Magic for the Announce Mods to work properly.