WoWDB

This achievement requires the raid to be split into Mogu and Mantid teams instead of Left/Right.  After completing their assigned room, the teams must cross up using the chains and drop down on the other side so do the same chest type again.  The chains take a full 20 seconds between each person (10 to pull up, and 10 seconds to drop back down), so it takes a lot of time for the raid to switch sides, so you need to split up that time between each timer.

Put the melee on the Mogu team and ranged on Mantid.  Kill the green boxes and the one boss first (using hero/bloodlust), then work on the mediums and the smalls.

When you’re nearing the end of your boxes and just have smalls left, start sending up players from your team on the chain to wait in the middle.  It’s probably better to send the lower DPS first.  Leave at least one DPS in each room to hit the lever, but wait until you have <5 seconds left on the timer before pulling it, giving yourself as much time to transfer as many people as possible to the middle.  Once the levers are hit and the timer is reset, people can drop down on their new sides while you finish transferring the remaining raid members, but DO NOT open any boxes until everyone is on the correct side.

Once everyone has switched sides safely, open the boxes normally and finish the encounter.