This is the item needed to obtain Quel'Serrar (https://vanillawowdb.com/?item=18348 https://vanillawowdb.com/?item=18348). You get this book (either through long days in Dire Maul or the Auction House) and you return it to the library. The follow up to start the chain for the Quel'Serrar is found here https://vanillawowdb.com/?quest=7508 https://vanillawowdb.com/?quest=7508

Edit: As of Patch 3.2.2, this quest may or may not be still completable. Since Onyxia was updated, the quest chain may have been set so that you can no longer start it. However, I will leave the guide posted in the event that you are still able to start and complete the entire chain.

Since I was a bit confused on how to help my brother with this, I figure I will post a mini-guide here on how you go through the entire process.

First, you will need to pick up https://vanillawowdb.com/?item=18401 Foror's Compendium of Dragon Slaying. This can be obtained either through a very lucky drop inside Dire Maul, or off of the auction house. The above average price was about correct; my brother paid 200G for his copy.

After picking up the book, use it. It will start a quest called https://vanillawowdb.com/?quest=7507 Foror's Compendium. In order to turn it in, you must go to https://vanillawowdb.com/?npc=14368 Lorekeeper Lydros, located in the northern section of Dire Maul. However, unless you have the https://vanillawowdb.com/?item=18249 Crescent Key, you are not going to get very far. If you do not have the key, continue reading from here. Otherwise, skip the next two paragraphs.

In order to obtain the key, you must kill https://vanillawowdb.com/?npc=14354 Pusillin, a boss in Dire Maul East. To fight him, go into Dire Maul East from the three-way split (Where you can access the entrances of all three wings). Upon entering the eastern wing, you should be set in the southeastern corner of a room where you can look down upon a grassy area. From here, head west along the path until hitting the wall, which you will then head north. There, you will find a friendly version of Pusillin.

Talk to him, and he will run away. Chase him down, and speak to him again. He will repeat this two more times until he is able to be fought. He will summon some adds during the fight, so be ready for them (They went down rather quick with my brother and I, so any form of AoE should suffice against them). Once he is down, he will drop the Crescent Key.

Now, head to the northern wing of Dire Maul. Once inside, head north into the grassy area where you will see a decent number of https://vanillawowdb.com/?npc=13036 Gordok Mastiffs. On the western side of the grass is a ramp leading west. Head down it, and use the key to open the door. This will open a rather lengthy path to the library, where you can turn the quest in to Lorekeeper Lydros.

Upon turning the quest in, you should be given https://vanillawowdb.com/?item=18513 A Dull and Flat Elven Blade. Accept https://vanillawowdb.com/?quest=7508 The Forging of Quel'Serrar from the blade, and turn that quest back in to Lorekeeper Lydros. He will now offer you the final quest of the chain in obtaining the https://vanillawowdb.com/?item=18348 Quel'Serrar.

The last quest, also named https://vanillawowdb.com/?quest=7509 The Forging of Quel'Serrar, is the funnest in the chain. You must now go to https://vanillawowdb.com/?zone=2159 Onyxia's Lair. This will require you to get a raid together to slay https://vanillawowdb.com/?npc=10184 Onyxia.

After beating on Onyxia until she is around 20% of her health (A guide to fight her is located on https://vanillawowdb.com/?npc=10184 her page), the Warrior or Paladin obtaining the Quel'Serrar is to drop the https://vanillawowdb.com/?item=18489 Unfired Ancient Blade between Onyxia and the main tank. It is required that Onyxia breathes fire on the sword that appears. Otherwise, you will need to abandon the quest, and pick it back up from Lorekeeper Lydros back in Dire Maul.

After Onyxia has been slain, and the sword has been breathed on, the Warrior or Paladin should then right-click the sword that appeared to receive the https://vanillawowdb.com/?item=18492 Treated Ancient Blade. They should then use the blade on Onyxia to complete the objective of the quest.

Following loot distribution, and whatever else you want to do, head back to the northern wing of Dire Maul. Go down into the grassy area, and down the ramp on the western side. Using the Crescent Key again, open the door and head to the library. Speak to Lorekeeper Lydros, and turn in the quest to receive your Quel'Serrar!

Now, for some tips and notes:

• Be sure to wait for Onyxia to drop down to about 20% of her health before dropping the sword; you only have a total of 20 minutes to pick the sword up and use it on her before it will disappear
• If you are having trouble getting people to go to Onyxia's Lair with you, let Death Knights know they are welcome to the raid. You can get a lot of DPS from the Death Knights, and they are just the right level upon leaving Ebon Hold to go help slay Onyxia.
• Be sure to allot yourself enough time to complete the chain; it may take you well over two hours to complete it if you cannot get enough people to go kill Onyxia, or even get the Crescent Key if you are not able to run yourself through Dire Maul.
• An added bonus to completing this chain is getting the https://vanillawowdb.com/?achievement=684 Onyxia's Lair Achievement, and having the chance to roll on Tier 2 helmets that you rarely see, and an https://vanillawowdb.com/?item=17966 Onyxia Hide Backpack, that has a total of 18 Bag Slots!

DOES count towards https://vanillawowdb.com/?achievement=1680 Loremaster of Kalimdor