Ok so its fairly simple, all you have to do is get infront of the DM west door and use eye of the beast. after that send your pet all the way east (across the arena towards DM east) of your location into a tiny blue room that i believe leads to the arena. after that, just stay in the first room and let Eye of the best run out. the door to DM west should be gone when the screen switches back to you. Make sure to walk through quickly, otherwise the door will respawn.