Hello there not 100% if this is a repost but I couldn't really find this exact thing if you find it a repost just don't rep me - it's basicly just me finding a new way to get under the world through icecrown citadel. I myself was bummed out when they fixed the last one so i found this one today and thought i'd post it.
And not sure if it belongs here or in exploration but seeing as i'm kinda flying through a wall i thought i'd post it here.
Fly in there under it's "cheek" this is way up btw like way up.
Then when you're under it's cheek you fly in the corner where the arrow is pointing
Then you fly over there and look straight down, don't go too far to the left or right or you might dismount as it's very close to the Halls of reflection entrance (You can go there and land behind the portal if you feel like it, nothing special tho)
Then you fly straight down and be sure to fly straight down or you'll most likely dismount and fall to your death.
When you see that spot you stop, and fly over the invicible wall and down the rabbit hole and you're under the world and you're free to do what ever, personal favourite is flying up under the ground and ganking someone.
I hope the pictures work, If not i'll get right on it.