Well, if you look at the various obstacles, the prerequisites are pretty clear.
You need to start with the room uncleared so you can hit the orb that opens the yellow door. (If it's cleared already, push a decoy to hit one of the seeding beacons.) You need to clear the room and drop all the trapdoors. And you need a spare keg and decoy to break the wall next to the oremites, as well as a pushing weapon.
This is pretty tricky and you'll need to make full use of the resources the room provides you.
Click here to view the secret text
×By which I mean, you'll need to get the kegs from every entrance that has them.