The Moldvay guidelines encourage a lot of "S" rooms on my map, which stands for Special. And what is a special? It's a weird encounter that isn't necessarily a trap, treasure, or monster, although it certainly could have those elements. Dungeons are not "normal" environments, and trying to fill a megadungeon with things that make sense, makes for predictability, which makes for boredom. Those "S" rooms are important.
Some of my "special" rooms are going to be deliberate reveals of information about the megadungeon. These are to give players some goals. Others are going to be ideas that I don't have fully fleshed out yet. Player interactions will help determine the direction I take them. Finally, some will just be plain weird and/or nonsensical. The players can make of that what they will. The only important guideline is that they should follow the level "theme" if it has one. This is a grim-horror-themed level, so there won't be much whimsy here.
I've explained about the God's Eyes a bit in this post: Orbital Gods. I dropped a broken one into the gatehouse, that just whispered incomprehensibly and then was silent. I think I'll drop in one that is in contact with a sinister entity. This raises a few questions: can this God's Eye contact other divine beings? is the sinister entity a god, or a devil, or something else entirely? can it be carted out of the dungeon? This is one of my not-quite-fleshed-out-ideas, so I'll see what the players do with it, and what inspiration strikes during play.
118. God’s Eye
This God’s Eye is a large black metal circle, 10’ in diameter, with an intact imaging screen. When the players first enter the room, the God’s Eye will be filled with the image of a giant, slit-pupiled eye, moving about, watching the party. The pupil is black, and the rest of the eye is a deep purple.
Anyone touching the God’s Eye must save vs. magic or be forced to attack the party for 1d3 rounds.
On subsequent visits to this room, the God’s Eye will only show the slit-pupiled eye on a roll of 1-2 on a d6. There is no ill effect from touching the God’s Eye while the slit-pupiled eye is not present.