They never defeated him, so no way to tell.

End of the fight?
He is pretty imba right now, or at least no one knows how to kill him.

But about the lore... not a lot in the start. You can see the sound files transcript in mmochamp, but is pretty lore soft.

So, imagine the setup of where you fight. You're on a giant balcony, with the gunship docked on one side where a teleporter is (so as to serve as a checkpoint). On the other end is a gigantic door leading back into the citadel.

As Alliance players start the event (and I was watching a stream, so I can only guess that you talk to Muradin), Saurfang Jr. walks out from the door and gives a speech about how when each person fell in all these petty conflcts, they were fodder for the Lich King's armies etc, etc. Muradin yells "A lone orc? Against the might of the Alliance? CHAAAAAAAAARGE!" Saurfang, more powerful than previous DKs, begins to force choke the entire army at the same time, and they float up into the air, whilst our favorite undead orc gives the best line ever: "Hahahaha......dwarves...." and then you engage him.

No clue what the exact ending is, though, since I didn't stick around to watch the stream too long.