Ok, so this is a simple one, you can use it in any dungeon.
There's a library or a room full of fireflies--and an arch.
On the far side of the arch there's stairs and at the bottom of the stairs a pile of people--dead on top, skeletons on the bottom, maybe some monster bites.
On the near side is your party.
Go through the arch, you get zapped with a mindstatic feedback, have a seizure, pitch forward join the pile. No save. Unconscious on top of dead people.
Party scout will probably find this out the hard way.
The bolt attacks the conscious mind. The only way to get past is by going through without any conscious mind. Basically you can get through it asleep or unconscious. Monks can go through on a successful will save or wis check or whatever mechanic you want.
One clue is the screen is used to catalogue your thoughts as you hit it. They get turned into (firefly room) a firefly or (library room) a book. Anybody reading the books or casting Speak With Insects (is that a thing? Speak with Animals. Whatever.) will find the last thought is "Ok, I'm gonna try to go through this arch…"