While doing quests and farming AV to get lvl90 faster i was asked to do a quest where i need to talk to some npc who ill let me use his kite in order to get to wall. There you get 2 quests, to kill 12 mobs Oosul-fire-warrior and Osul-veteran-archer, they are part of Off The wall quest and 2nd quest is to collect 8(?) items. While killing them I noticed that they respawn almost instantly and die pretty fast ( I'm lvl89 frost DK ). Also each mob u kill will give you about 33K experience. In a 30min I was killing them i got 4mill experience , thats 8mill/hour and there is practically no downtime at all. Only bad thing is that mob cant be looted ( so no loot at all ), but they give xp and thats not bad.
Also I am not sure if they are phased/or you need to be on that quest to see them, if not then you can ask a friend to get you there on a 2-seated mount.
Location on the map, there are also coordinates in case you need them.
You can see amount of XP I had before i started to farm them on that picture.
After 30min of farming...
P.S. Sorry if this is repost, i searched by the name of the mobs and location....