i would love to help out but the dungeon is pretty long and its hard to understand exactly whats your problem, probably follow a guide on youtube?
I'm curious about this too.
There's quite a few reflectors in the game.
Do you mean the huge reflector in the main hall, that activated only when both abyss gems are installed?
If so, you have to complete a sliding piece puzzle to create an image to activate the reflector to open the Large doors in the main hall/stairway
Ok so lemme try to explain it more.
I just started the dungeon, i fell through the floor, beat the anubis mini-boss, and collected both of the abyss gems. The problem is that i dont know what to do with them. I know there's a puzzle, bit how do i get to the puzzle?
You are probably missing the button that lets you move forward.
Find this spot on your map. In this image, right above Fox, is a climbable ledge that lets you press a button that fires an arrow at a cracked wall.
From here, you continue on the path and it should take you down the path of getting 2 glowing orbs.
In the room with the second orb, there are two doors. The one you came in at, and the one you want.
Leaving through the second door will lead you to a place where you can use both glowing orbs.
Yeaaaahhhh i was in the room but for some reason never saw the pedistals, and if i did i just thought they were breakable items