I am not sure if this can be counted the same, but a good portion of this exploit was posted a year ago --> http://www.ownedcore.com/forums/worl...ers-guild.html (Rogue shadowstep into Brawler's Guild)
A quick rundown first; You can shadowstep into the Brawler's Arena, but you have to be jumping at an angle where the target is fully visible (So no walls and such). Doing so will port you in, but as you can quickly find out, you cannot assist in the fight other than passive buffs like Swiftblade's Cunning or Drums of Rage.
Example: https://i.imgur.com/twSg8Wt.jpg
Now, for the thread's purpose. I was playing around doing this in the Brawler's Guild with my friend (seen above), who is stuck at the snake Nibbleh. I keep dropping in to give him the added haste and drums, but he keeps failing. One time, I shadowstep in before the boss spawns. I get ported out before the boss spawned, and Bizmo yelled that the person failed, porting them out. I thought it was just a bug. So, I tried again and again, trying to get the timing right. The timing seems random, but as long as I pop in and get booted out, the fight resets after a few seconds. I was able to repeat the trick about 4 times out of 10, so it's not exactly guaranteed, but it does happen.
1. Spec into Shadowstep
2. Target a player who has just entered the arena, and use Shadowstep on them.
3. Watch as they (hopefully) get ported out.
Just remember, this DOES count as griefing. Do it to friends, not random people. Got some nasty hate mail for doing it to a random person, which was funny, but still. Mind your exploiting manners.