Updated Wed, Nov 19, 2008 by Messiah
Once you get going in the Wrath of the Lich King (WotLK) expansion, it does not take long before you run into many of the instances that are available for players to adventure in. Azjol-Nerub is the third level-up instance in the expansion and is located along the north-western edge of the zone of Dragonblight. This instance is a part of what once was the empire of the spider like Nerubians. However the Lich King has largely destroyed their empire and slaughter the Nerubians. While it is only a small part of their vast underground empire, it is intimidating in its own right. The area is also infested with the scourge as they remain there from the war with the Nerubians.
To get to the instance you must enter an underground cavern and either drop down a hole to the meeting stone and instance portal, or wind your way down a ramp and risk getting lost in the labyrinth of tunnels. Dropping down is probably the easiest way, but one you do you immediately come face to face with several of the Nerubians, luckily they are friendly.
The Nerubians that you find are right beside the summoning stone and will provide quests to you once you are the proper level for the instance, which is level 72 to 74. Right beside the stone and quest providers is the instance itself, which is very convenient. Also, if you look down the tunnel just to the left of the stone you will see another instance portal in the distance, that one is to the slightly more difficult Ahn'kahet: The Old Kingdom meant for players level 73 to 75.
Most of the mobs Azjol'Nerub are either spider based or undead (or both at once). In addition to the trash mobs in the instance there are three bosses: Krik'thir the Gatewatcher, Hadronox, and Anub'arak. Many players will recognize Anub'arak from his appearance in Warcraft 3: The Frozen Throne.
The first boss you come across when you enter is Krik'thir the Gatewatcher, whom you reach very quickly after entering the instance. In fact you can see him after only a single pull. Once you reach his room there are four groups of MOBs to clear and then you fight him. Once you pull the first of the four groups it starts an event that leads to each group coming in turn and then the boss. Once he attacks he has several abilities that you need to watch for including: mind flay, summoning adds, and an AoE curse.
The curse he applies is called Curse of Fatigue and affects the target and anyone within a small radius. He casts it at what seems like random targets at intervals throughout the fight. It hits the target and those around it for roughly 3000 shadow damage and a 10 second debuff that slows movement, attack, and casting speed. It makes it important to keep separated during the fight.
Throughout the fight he will also summon a number of insect adds that can just be grouped up and AoE'ed to death. Lastly he enrages when he is near death and hits harder and faster. The fight is slightly complicated due to the fact that you want to group up for AoE'ing the adds, but need to keep your distance for the curse.
The second boss is also a scripted event. When you enter the area you face a large armoured beetle type MOB called an Anubar Crusher and various other adds. In this area you are walking on spider webs, and if you look down you can see the giant spider Hadronox below you. As soon as you engage the first group with the Anubar Crusher the event starts and the boss starts moving up its web. You need to kill the first giant beetle and it's guards, then two more groups appear, which also need to be defeated. Once they are, spiders continue to spawn occasionally and Hadronox should be near the top.
You engage Hadronox as do the MOBs in the area. You need to control not only Hadronox, but the adds as well, which will attack you or him. The issue with the MOBs is that any time one attacks him and he kills it, he gains health. So, if you let him continually attack them, he will regenerate to full health very quickly.
Hadronox himself has several abilities including a web attack that pulls players and MOBs closer, another web attack that immobilizes players, and an AoE poison attack.
The best way to fight him seems to be clearing the initial 3 groups that include the crushers, then allow Hadronox to continue to move up the tunnel. Pull back and wait for him to clear the adds that are accumulating there, then when they are all dead, pull him back to the entry ramp and fight him there. Without the adds adding in, it becomes a much easier fight.
Once Hadronox is dead you descend down his web and find a hole leading downward. Once you enter the hole you fall a long way down into a pool of water, where you see an ancient temple in front of you. Make your way to the temple and engage the two guards that must be defeated before facing the last boss, Anub'arak.
Anub'arak is another version of the giant crusher beetle and has a few abilities to deal with. You must DPS him down to intervals which seem to be 66%, 50%, 30% at which points he submerges. While submerged non-elite and elite MOBS spawn. You must clear the elite MOBS to have him resurface. While underground he also launches spikes up through the earth that cause damage and fling anyone on them into the air. They are relatively simple to avoid though, just watch for the ground bubbling and move, you have about 2 seconds warning. When he surfaces for the last time he will enrage near death.
After you have defeated him you are done in the instance. Continue past him and you can find a quick exit portal, since there is no way back up to the way you entered.
The instance is extremely fast, essentially being three scripted guard and boss fights with single groups of trash in between each one. Including the groups of guard MOBs that trigger each boss fight there are only 9 packs of MOBs in the whole instance! The entire instance can be completed in roughly 30 minutes. The instance is very well laid out and is extremely visually appealing. Most groups will find this an extremely entertaining instance. Great job Blizzard!