For the non-Brady peeps, this puzzle is quite aggrevating. Most of what people say about the correct color order is incorrect. After being "punished" by the undead about 8 or so times, I finally managed to piece together what the riddle in the punishment room means.
Here's what the four pillars say:
1) Begin with the color of night.
2) For the second, look to the flame that gives the earthbound people wings.
3) The third is also of the flame, denying the earthbound their wings.
4) Something about a sacrifice, meaning you must activate the correct Sigil of Sacrifice.
Now if you remember climbing up the Pharos:
1) The First Ascent made you break the Night seal, so black is of course first.
2) The flame which gives wings is green, signified by the Brainpans you had to kill to climb the Pharos.
3) The flame which denies the wings to the earthbound is red, like the red flames from the red magic pot things you had to avoid (which, by the way, fuck Reddas and his gambits hardcore).
That's all the easy part. The correct sigil to activate for the last is a little tricky unless you take the meaning of the final pillar in the punishment room word for word: "That which you sacrified."
Remember the Second Ascent when you activated one of the pillars to lock a certain ability? The correct Sigil of Sacrifice to activate will be the color that matches the lock you placed on yourself in the Second Ascent. Personally, I locked the Altar of Knowledge (which takes away your minimap), so the Sigil that I activated was pink (color matching color of the Knowledge seal) and it worked!
So the correct Sigil of Sacrifice should vary as follows:
Purple: If you locked magicks.
Pink: If you locked knowledge.
Yellow: If you locked wealth.
White: If you locked steel.
From there I was able to read the final pillar, which says to ignore the sigils from that point on. On this section, you'll be looking for a normal Way Stone behind a Fool's Facade.
Just a bit of clarification for you all. ^-')b
Don't be stuck in that fucking pit like I was.