[npc=77093] flies around the Crimson Fen and you need to attack him when he lands somewhere. A good place to wait is the rock outcrop at 52, 62, south of High Pass and northeast of Beast Watch. He will eventually land there, making it an easy matter to kill him (well, relatively - he is still a 93 Elite with 539,280 HP).
He drops the following quest items:
[item=113459], which starts Trophy of Glory: Roardan the Sky Terror (Horde)
[item=113458], which starts Trophy of Glory: Roardan the Sky Terror (Alliance)
Killing him is also part of the requirements for the achievement Gorgrond Monster Hunter.