_{An entry in Fortnightly Topic Challenge #39: Deep Down in the Dungeon 1.tl;dr at the bottom}

You and your wacky group of adventurers barge through a hidden door and end up in what looks to be the start of a corridor. The door slams shut behind you, leaving you in darkness. Despite your group's best efforts, it won't budge! You're stuck. You take a step forward and suddenly torches that were mounted on the walls light up, one after another in a rapid spree until you can see everything! Well, at least everything in this section of the hall. Looking to your right, you see words carved into the walls -- it reads:

Hah! You think you’re so clever

Believing you’re done at last

Well I’m eager to tell you

the worst has yet to pass

Cannot go backwards, cannot escape

Forward you go, press down a plate

Correctly guess, choose the right shape

On you’ll continue to decide your fate

A Corridor with panels and traps of killer gas

No tricking, avoiding or escaping its grasp

Keep in mind those before

And let their remains warn you

Because there’s no second chances here

As you finish reading it aloud, the group collectively outbursts in despair, "NOT AGAIN!".

What you thought might be a treasure room or an escape out of this unrelenting cave system is actually another trap. DARNIT.

Whelp, there's nothing to do but continue onward as it said. You walk down a bit and reach a pile of dead bodies...which really doesn't look promising. Looking to your left you see four square plates embedded in the wall. An Eye, a Pyramid, an Ouroboros and a Drop. 3 are pressed in, but one of them (which has a Pyramid embossed on it) is still protruding.

After some discussion, you have all decided that the 3 plates that are already pressed in must have released the killer gas and not reset. At least something is FINALLY working in your favor. You press the Pyramid plate down and something clicks....but nothing seems to be happening.

You take a hesitant step forward and aren't dead yet...so you all continue on. As you go down the corridor you find random bodies littered around in various states of decay, perhaps they tried to outrun the gas or who knows what, but they are definitely dead.

You come across another pile of bodies, with another 3 plates pressed in and another Pyramid remaining protruded. You press it in, hear another click, and continue on.

This cycle repeats a few times and you're feeling like your luck has finally changed! All these people died so you don't have to! You proceed to press in a Drop, an Eye, Pyramid, Ouroboros and a Drop, each with great success.

Everything is going swell...until you reach the 8th panel. Only two are pressed in. Uh oh. 50/50 chance. What are you going to choose? The Ouroboros or the Drop?

If you make it to the next section, you will find that only one will be pressed in, the Pyramid.

And if you make it past that, you see the end of the corridor, you're almost there! However...there is one more set of plates on the wall and NONE of them are pressed in. It seems you're the only ones who have made it this far...so now what. Which one will you press?

Map is a visualization of the corridor. Bloody marks are where the panels are and the final panel is marked in green at the bottom.

TL;DR: Which plates need to be pressed in to get past the last three sections and why?

Hint 1

Hmm well what exactly is a corridor?

Inspired by The Thirteen Doors of Aj Noc'la by Alconja

One thing I noticed about this puzzle is that:

Corners are important.

So, let's take a look at this map.

If we count the corners before each panel, the numbers we get are 11, 15, 21, 34, 43, 48, 57, 64, 70, and 77. Using the insights from Zenth's answer and Braegh's answer, we can use these numbers to complete the puzzle.



11 mod 4 = 3 --> Pyramid

15 mod 4 = 3 --> Pyramid

21 mod 4 = 1 --> Drop

34 mod 4 = 2 --> Eye

43 mod 4 = 3 --> Pyramid

48 mod 4 = 0 --> Ouroboros

57 mod 4 = 1 --> Drop

64 mod 4 = 0 --> Ouroboros

70 mod 4 = 2 --> Eye

77 mod 4 = 1 --> Drop


So the last three panels are Ouroboros, Eye, and Drop!

Also, this was a great puzzle!

I have some ideas about the shapes:

The Shapes and Iconography lead me to believe there is a number
correlation to the symbols. Since the icons each have a place where
they come to a "point", and they are written in this order on the
image from left to right.


Ouroboros = 0

Drop = 1

Eye = 2

Pyramid = 3


This leads to some issues though in discerning the pattern, I'm
working on trying to relate it to the map, and only prior information,
but not making too much headway.

With regards to the map, I'm wondering if the red marks where the panels are are "accurate". Specifically The first bloodied area could be on a flat or a point of a "triangle" pattern that would fill the room. (I've done numerous space walking patterns that almost fit but usually break down later in the hall.

The Legend

For the entirety of my answer, please refer to the legend below:

P = Pyramid

E = Eye

O = Ouroboros

D = Drop

Feedback

This is a great puzzle! I really enjoyed reading the story, and it has sort of an Indiana Jones feel to it! +1 From me!

Some Ideas

@Zenth brought forward a brilliant idea that the plates are in a numerical order based on their positions on the map. This order is:

O = 0, D = 1, E = 2, P = 3

Considering the fact that most human beings use a $1$ based numerical system, I believe it will actually correlate to:

O = 1, D = 2, E = 3, P = 4

@Stigeon also brought forth a good idea to use mathematical operations to discover the remaining plates which would be a really cool solution to this.

• I ran the sequence through online solvers in both bases:
  
  
  • 
    Altered Qualia's Sequence Solver: No Result
  
  
  • 
    Wolfram Alpha Pattern Analyzer: No Result
  
  


• The four basic mathematical operations were fruitless resulting in:
  
  
  • 
    $0$ Based: $13$, $-7$, $0$, $ERROR$
    
  
  
  • 
    $1$ Based: $20$, $-12$, $768$, and $0.021 (Rounded)$.
  
  


• The pattern doesn't seem to have anything to do with placement in specific sections.


• The side each plate is on doesn't seem to have any significance either.


• The pattern also doesn't represent a palindrome, modified or otherwise.

My Answer(s)

Currently, the plate order is as follows:

P, P, D, E, P, O, D, O/D, O/E/D, O/E/D/P

Partial Answer

I suspect there might be some hints hidden in the text:

"Keep in mind those before"

I suspect this is referring to the previously pressed PLATES and not the dead adventurers.

"and let their remains warn you"

If we're going along a number sequence track - could "remains" be referring to remainder-after-division aka modulus?

Let’s assume that

previous adventurers, when confronted with this corridor, would either (a) press one plate down at each panel or (b) attempt to move past the panel without pressing anything, possibly shifting from strategy (a) to (b) at some point which may or may not be survivable. Let’s also assume that reasonable adventurers would not try multiple plates or start to push plates after surviving without touching one. Unspoken assumptions such as there’s nothing apart from the adventurers that’s interacting with the panels also apply.

We observe that