This is basically for unlocking Pack a Punch aka the ubersprengen. Simply said, you will need to use every teleporter while a red button/stone on a wall opposite one teleporter is pressed. Each time done correctly, the Ubersprengen will slowly rise from the floor in the room which you will be teleported to temporarily. After doing the 3rd teleporter, you will have PaP unlocked as well as the achievement for the entire lobby.
First open up the entire map, so that you can access all 3 teleporters. Now press the button use the one at spawn, press the button again and use the other 2 teleporters.
- one at spawn
- one more or less beneath the planet-system required for the broken flail (about 30 seconds into the video)
-one is next to the blood pool/blood altar where you do the last step for the shield upgrade (about 1 minute into the video)