How you can win the Highmaul Coliseum easily !
What you need ?
3rd Party Tool -> Wallhack/Flyhack
href="http://www.wowhead.com/item=111820/swapblaster" rel="nofollow" style="-webkit-box-shadow: none !important; box-shadow: none; font-size: 13px; text-decoration: none;" target="_blank">Item - Swapblaster (Nerfed to 1min CD with Patch 6.1)
Peerblock -> Block your home realm IP.
Guide:
Queue up to the scenario.
Enable Peerblock and Wallhack/Flyhack, in the Dungeon.
Swap all players to the black hole and they cannot join the fight.
When you are the last one, leave the raid for nobody can report you and wait, until the encounter started.
You will get the achievement instantly ! Easily Win !