So... this thing does some pretty funny things.

It's hard to go into much detail without some spoilers, but among other things your whole party can probably ignore a particularly annoying encounter mechanic in Dunwich as long as the fastest-cycling deck has ONE copy of this card. And when searching for dream cities in the dreamlands there's another trap you can just waltz through. When this card works, it tends to be the key to your Locked Door.

It's very likely you're going to blank the discard condition for the card, so it is a stall unless you can push the game state to the point where something is either less relevant or irrelevant. That happens a lot though. And its cheap as dirt if you don't need the slot.

This becomes a must pick for high draw seeker decks in Dunwich Legacy.

Slot pressure is usually only to dream enhancing serum, of which you only need one. Orphic Theory can essentially block everyone's favorite treachery, beyond the veil. This ends up being a very strong counter to that card, as you can proc Orphic Theory just before you meet the criteria for Beyond the Veil to trigger. It breathes life into high draw seeker decks, which used to have to spec into Versatile -> Deny Existence to run that campaign.

Outside of that, it has some pretty great uses still for most high draw seekers. A couple of treacheries that come to mind are Arctic Wind (an absolute bane to high draw seekers in EoTE) and the possessed treacheries in Carcosa.

Overall, definitely don't count it out. If you're in a campaign with "safe" treacheries Farsight still probably wins the slot, but at 1 exp it's a godsend for those bad ones.