Look at that, twice in two days! I'm on a roll. Also, this is the second-to-last one of Questes, so let's make it count with the flat out coolest piece of audio work in the game.
Who can do this?
This is a horde-specific questline, but don't let it discourage you - it only requires level 15 to do, so you might as well level up some race/class combination you haven't done yet (easiest is BE or Undead, location-wise) and you can do both WC for The Glowing Shard and then this in one demonic, or even fel, swoop.
All Credit to http://www.wowhead.com/item=22597#screenshots:id=55354
Where do I begin?
It can be annoying, or it can be easy. I've never had an issue with getting the item that starts the quests - The Lady's Necklace, dropped off of Fallen Rangers and Deatholme Acolytes at Windrunner Spire in SW Ghostlands. However, a select few have just very poor luck and end up farming for a while before it drops. It's just the luck of the RNG, but it's always dropped within 3 or 4 kills for me.
How does mine necklace?
Seriously? This is like the simplest quest in the history of simple quests. Just read the bloiting quest text. I'm not even linking to wowhead here, it's just that easy.
And now, the loot.
You guessed it! Loot.
First off, you get 100,000 rep with Tranquillien, and 250 with Undercity. Toss on a sprinkling of gold and xp, and it's not a bad quest in and of itself. After the completion event, you also get a book, if you talk to the nearby question-markless Ambassador Sunsorrow. More on this later.
That's it, though - there's not much here. Of course, as we know, the journey is the worthier part.
All credit to WoW.com this time.
So... What's the point?
If you've done it by now, you know the point. At the end of the quest chain... *SPOILERS*... Deathwing appears and blows up the Undercity! Haha... see, now, the people who haven't done it are now going to go and complete it before actually having it spoiled. What really happens is that Sylvanas and a few of her banshees sing an epic and stunning song named 'Lament of the Highborne', all in Thalassian. I doubt that something of this quality will disappear in Cataclysm, but it very well could disappear, at least in its current incarnation - as Undercity and the entirety of Northern Lordaeron is getting hit by the renovate-bat, who knows.
For those allies in the crowd who can't be bothered to level up a measly level 15, I mean, seriously, you could just make a death knight for A'Dal's sake, you can type
into the text window to hear the song, or watch a video on youtube. There is, however, nothing quite like walking up to the throne room and seeing it live. This is one of the truely amazing artistic feats in WoW - and something not to be missed.