If you haven't been there before it can be kind of a maze. There is a top level that has 6 mini bosses on it that have to all be killed to open up a room, then that room has to be cleared to kill the end boss. If you just care about exp you might not go after the last boss, but he does have some good drops.

The best way to clear the top is to just spam AE rank 1, until you get to a mini boss, you will do this 6 times, and you mainly do it to unlock the big room that is great for aoe grinding. This is my main trick for aoe grinding, that way I can keep my alts on follow and if they aggro anything they will just get caught up in the aoe.

Once all 6 mini bosses are down, you jump down and start in on the dragons. First pull leave your alts up on the platform. Then round up 3 groups, ice block, frost nova, blizzard. bring your alts down and repeat for the other 8-10 groups. There is one group of dragons down a hallway, that only becomes an issue if you go to the final boss. This right here is probably your fastest exp grind. you could just run in do this and reset. You can probably do 5 groups at a time, but I would start with 3 to get your technique down, and to see how hard they hit.

Once all the dragon groups are down, there is a big room of undead with a boss at the end of the room. Same thing, Block, nova, blink, blizz. These guys hit kinda hard, but you should be find with your pvp gear. You can do this in 2 pulls comfortably, maybe one. Ton of exp here. Don't try to get the boss with your big pull, he can do some annoying things(don't remember what).

From here you will have some big dragons flying around you can take out and the final boss. If you see a hallway with windserpents down them skip those hallways you need a quest to unlock that boss.