Apologies if this is a repost, I searched and browsed the past few pages and couldn't find it.
Unfortunately the first way I've found to get out of Sunwell Plateau and jump down to instanced Isle of Quel'danas is past about 5 or 6 trash pulls, so this is really only for guilds killing Kalecgos or farming the initial Sunwell trash. Some of you might find these screenshots I got interesting though
1. First, find this spot which is just around the corner from the entrance of Sunwell Plateau.
2. Walk up the stairs and stand in the same direction and on the same spot I am. Delete your hearthstone, and use the auto-unstuck tool. NOTE: Mages can also blink through instead of using the unstuck tool.
3. If all goes to plan, you should be standing here! If not, wait 5 minutes for the unstuck cooldown and try again. Make sure you're standing exactly where I'm standing facing the invisible wall.
4. Now, turn to the right and simply jump down into the Isle of Quel'danas.
5. You made it.
Now that you're here, there is a lot to see. In an hour or two of looking around, I managed to find a way to see M'uru trash mobs, get to Brutallus without clearing his trash or killing Kalecgos (you're even able to walk right up to him because he isn't targettable until you start an event where he kills a dragon), get underneath the Sunwell, see the Twin Eredars room and even get into Kil'jaeden's room.
Here's how to get underneath the Sunwell, and into Kil'jaeden's room.
1. Find this spot. It's along the Eastern side of the Sunwell. If you were looking at the map of the Isle of Quel'danas, it's somewhere around the co-ordinates 50,54.
2. Simply walk through it. That wall doesn't exist, it's an illusion.
3. Turn around, you're underneath the Sunwell! From here you can see many things, including M'uru trash mobs (you stand underneath them), you can walk out to Brutallus, and you can see the Twin Eredars room. However, I'm going to show you how to get to Kil'jaeden's room.
4. Notice the huge hole in the center of underneath the Sunwell? Kil'jaeden's room is actually there, you just can't see it. Mount up, and face the center of this hole. Run towards it and jump into the hole.
5. You should find yourself here, on a pink floor. Admittedly, it's not actually Kil'jaeden's room. It's underneath it!
6. Look up.
Here's a bunch of screenshots of all the places I managed to get to that I haven't described in detail up here.
1. The entrance to Magister's Terrace. Walking into the instance door didn't do anything unfortunately.
2. Brutallus! I could walk right up to him without getting hurt, as he wouldn't engage.
3. Something a little strange happened when I went underwater, all colour disappeared and this is all I could see.
4. There's a gap in the wall of underneath Kil'jaeden's room. I jumped out of it. I kept falling and falling until I died, but even then my body kept moving until I hit the water. Looking back up, I could see all of the Sunwell. Kinda cool.
5. Looking up at the Twin Eredars' room from underneath the Sunwell.
6. M'uru trash. Two pictures, first looking up at them from underneath the Sunwell, the second looking across to them from a cliff near Magisters' Terrace.
Enjoy! And feel free to ask any questions.
[Guide] Exploring the Sunwell (instanced Isle, Kil'jaedens and Twins room, M'uru)
