Kuwaq Yaku – The Forge DLC
Forge of Destiny Challenge Tomb (part 5)

Return down the stairs to the jaguar-head switch and use it to turn on the gas jet near it.

Move into the doorway to the left of the switch and the gas jet...

...jump back down onto the ledges surrounding the tower, and re-enter the center room.

Now to raise the ledges to the THIRD LEVEL permanently. Start by jumping onto the counterweight again to raise a ledge outside.

Drop down and run through the doorway on the left. Turn right...

...and shoot the gas jet with a fire arrow, just as you did before.

The explosion propels the ledges up and around counterclockwise.

As the ledges move, turn around and run forward onto the next ledge.

This time don't jump into the doorway. Instead, wait for the gas jet to the left of the doorway to cycle on...

...and shoot a fire arrow into the gas cloud.

The explosion rotates and raises the ledges up to the THIRD LEVEL, where they once again lock into place.

You can't linger here though. The ledge ahead collapses, and soon after the ledge Lara is standing on also collapses. So turn around and run back the way you came.

The ledge in front of the doorway is safe, and there's a checkpoint here.