Henleber quickly secured himself to the piton using his sling and tying it off to his belt and then got a grip on the rope with one hand and tripped the floor levers with the other. As the floor fell away, he pulled up the rope and grappling hook and then reflipped the levers leaving himself in the same situation as a moment before, but now with his rope.
Athletics Check (as needed) 26

Tripping the levers back into the down position results in the ceiling trap door closing and the floor trap door once again releasing. Light from the still lit torch below shines up as you recover your rope.

Henleber finished coiling his rope and tripped the levers again to reset restoring the floor and opening the trapdoor above him. He then used the rope and grappling hook to climb through the trapdoor and emerge above.

Athletics Roll if needed: 13

You emerge into a small tunnel, scarcely large enough for you to crouch or crawl through. It is pitch black in this tunnel, but seems to only go in one direction from here.

I light another torch and continue down the tunnel cautiously, pushing my pack 20 feet in front of me with Mage Hand to trigger any traps. My rope and grappling hook are at my belt and the lit torch is in hand. As I proceed, I try to puzzle out what type of tunnel this is and what sort of further traps might await me.

Dungeoneering Check to see if I can tell anything about what type of tunnel this is or where it might go. 11

The featureless tunnel holds no secrets to tell. It winds to the left and then to the right and the entire length of the thing is about 70 feet or so before ending at a door. It does not appear locked, though your knowledge of dungeoneering tells you it probably only opens from this side.

Henleber opens the door carefully and peers out. Once it is open, he will attempt to block it open so his retreat is not impossible.

The door opens into the bottom of a 10 by 10 foot pit filled with spikes with an open top.

What do you attempt to block the door with?

I take one of my pitons and drive it into the floor so that it provides a doorstop preventing it closing. I then use a hammer to break off enough spikes to make it safe for me to climb out using rope and grappling hook. I then climb to the top.

You successfully wedge open the door. Breaking the spikes on the other hand is more difficult. They are made of solid iron and hold up to your hammer's blows. However you find that you are able to stand up easily enough without breaking them so that you can climb out of the pit.

Climbing out of the pit itself isn't too difficult, however coming to terms with what you see once out is. You find yourself in the opening hall of the tomb. You vaguely remember this hall, having passed by here before. The colourful mosaic walls, the winding red path on the floor, the cryptic message from Acererak, the green devil and its gaping maw, the misty archway that led to your downfall...yes everything is vaguely familiar, except the two beings standing before you. One, a giant grey-skinned warrior of some type who stands towering over even you, his head not far off from reaching the ceiling, and the other, a short and stout dwarf clad in impressive scale armor adorned with religious symbols.

Your attempts to poke your dwarf friend are met with little success as he does not seem to notice them. Thibor does appear to be deep in thought, or perhaps in some kind of trance. As you continue to try and grab his attention, you hear the sounds of metal clanging from inside the pit you last climbed out of. Before you have a chance to investigate, a gaunt looking Eladrin man clad in a strange dark cloak climbs out of the pit.

As you stand there deep in thought pondering the meaning of these puzzles, a gaunt looking Eladrin man clad in a strange dark cloak climbs out of the pit closest to you.

Thievery Check 31
Perception Check if Needed 13

Your tools of the trade and skills at thievery allow you to easily press the catch of the box without being pricked by the poison needle hidden within. In doing so, the front face of the box swings outward on its hinges, opening up and hanging down to reveal the inside of the box. Inside, however, you see nothing. A small empty box.

While over there, he removes the poisoned needle from the box and uses it to coat his shortsword before returning.

Perception Check: 15

You successfully coat the tip of your blade with a tiny amount of poison. You do see other depictions of demons and fiends throughout the hall. Mostly the ones enslaving mortals in various places.