When the fight is over, the spikes retract—but only temporarily. Climb the ledges to the upper left as the spikes begin popping up behind you.

The upper ledge is higher than the others. In the single-player game, use the grapple ring above to climb up.

In co-op mode, use the bubble shield and grapple to get everyone onto the top ledge.

Head to the right as more spikes encroach from the left. The last red skull (5/5) is sitting in the near left corner of of the skull tiles with pop-up spikes just ahead.

To get it, run onto the first clear tile on the left, make a U-turn around to the right, snagging the skull in the process, and then turn and run forward along the clear tiles, taking a slight turn to the right near the end to avoid the permanent spikes. If you found all of the skulls, you'll get the VULNERABLE BRONZE RING OF ABUNDANCE (Ammo Efficiency+, Speed+, Weapon Damage+, Defense-) now.

Beyond the skull tiles, is an elevated walkway leading to the exit. Run forward as more spikes pop up behind you.

Move through the bag of gems on the low pedestal to open the exit. If you're attempting the time trial, keep running through the exit. Otherwise, stop and gather the goodies.

If you missed the last red skull, it's possible to go back for it once the spikes on the walkway retract. You'll die in the process, since you must block yourself in with spikes. The checkpoint on the ledge below will reload, and you'll need to repeat the final run to the exit, but it may be worthwhile if the skull is all you're missing

[Part 1 | Return to the Tomb of the Torturer Walkthrough]