When you go down the stairs again a couple of metal jackets attack you, they won't be any threat with the Beam Reflexor. When you enter the room with the dark idol; approach the door on the right for a cutscene. There's more metal jackets in this corridor too up until you enter a large spacious water-filled room with a light-and-dark (yin-yang style) energy pattern in the doorway, of which you need 18 total to open the door at the other end of the room. Before you go deeper into this room, go left and pick up the one hidden in this alcove here.
This is mostly a training section for your jet board, so equip it and follow the on-screen instructions as you pick up each energy thing. After the few in the middle take a sharp left and head up the ramp, you'll have to grind a rail twice and jump over a few gaps. After getting all of them the door opens, so proceed onwards until you see the oracle again who gives you another light power; Flash Freeze.
Use Flash Freeze to slow down the flipping platforms and quickly get across them, equip the jet board for the next obstacle course until you a reach a room with another light eco vent. In this room you have to slow down time again and quickly cross the beam in the center, with the blades, that spins really fast normally. Just keep jumping as it still spins around pretty fast, do this three times (you'll get to a new vent each time).
The last obstacle is a long stone bridge, which will collapse as soon as you stand on it. Use flash freeze one more time to be able to cross it with a little less trouble, you will still have to keep jumping from stone to stone to reach the end though. After the bridge enter through the elevator and begin the next mission; "Travel through catacomb subrails".