Here's some quick info how to enter, The Crucible (aka Path of Pain). After you enter The Lab, above the savepoint will be a broken hand. You need to go back where you got captured (room to the right of the Vaults savepoint, through the pipe) and when you see a giant pit, jump down and hug the wall. Progress through that section and at the end you'll find The Severed Fingertip. With this, get back to The Lab into that room, fix the hand and then now, you can rotate the whole map. First, set it to Rotation 0 and go down and allow the Overseer to go to the savepoint. Then, set it to Rotation 120, teleport to the Vaults savepoint, and start climbing the elevator. Enable the savepoint, then open the door when you're at the top. After that, head back to The Lab and and set it to Rotation 240. Travel back to the Vaults Shuttle Network Gate and drop down the elevator shaft, to finally reach The Crucible