This is the conclusion to the Scryer version of the Book of Fel Names chain, which gives Aldor/Scryer rep as well as some nice blue rewards. If you complete it, you can choose from:
Ceremonial Kris (+heal dagger)
Slayer's Axe (2H +str axe)
Sunfury Legguards (+AP mail pants)
Hauberk of Karabor (+AP leather chest)
Summoner's Blade (+dmg sword)
Wildcaller (feral staff)
As with the Medallion of Karabor line, this chain starts different depending on whether you're Aldor (A) or Scryer (S). All the quests are rated level 70 - though the chain is available at level 68, it sends you to the Shadow Labyrinth to kill Blackheart, which you might want to hold off on until level 70.
Aldors pick it up from Exarch Onaala at the Altar of Sha'tar:
1. (A) Karabor Training Grounds
2. (A) A Necessary Distraction
3. (A) Altruis
Scryers need to visit Larissa Sunstrike at the Sanctum of the Stars:
1. (S) Karabor Training Grounds
2. (S) A Necessary Distraction
3. (S) Altruis
Here the chains converge on your old friend Altruis the Sufferer in Nagrand. He gives out three quests that need to be completed (in any order) before you can continue:
4a. Against the Legion - Netherstorm
4b. Against the Illidari - Shadowmoon Valley
4c. Against All Odds - Zangarmarsh
Having gone around the world killing stuff, you can now return to Altruis and receive:
5. Illidan's Pupil
which leads directly into
6. The Book of Fel Names
Now it's time for a venture into the Shadow Labyrinth to kill Blackheart! Once that's done that and his body has been looted for the book, it's back to Altruis where again the chains diverge depending on your allegiance.
Aldor:
7. (A) Return to the Aldor - back to Altar of Sha'tar
8. (A) Varedis Must Be Stopped
Scryer:
7. (S) Return to the Scryers - back to Sanctum of Stars
8. (S) Varedis Must Be Stopped
Varedis Must Be Stopped is the final part. It's a 5-man group quest that sends you to the terrace outside the Black Temple to kill four elites: Varedis, Netharel, Theras and Alandien. Look them up for co-ordinates and tips on killing them - they're pretty straightforward, really.
When they're dead it's a simple matter of returning to the questgiver to choose a prize.