I think best use is for a seeker/survivor with scavenging+resourceful (so you can pick back scavenging) and pair this with short supply, and a lot of survivor cards that can be used from discard or gets advantage of discard cards.

I think the biggest problems are the weaknesses. Basically in 15 rounds you go through the same size of your deck with this card as without it (not counting tutoring). You get +15 cards but mill 15 more so it nets 0. So it is nearly the same chance to see your weakness. But if you draw your weakness you have to discard your other card (as you have to discard 1 but you cannot discard weakness) so you lose your chance to choose one. So the main problem is if you draw your "best" card and a weakness at the same time.

This card is good Survivors with high agility like Rita, who likes this for her passive, or Guardians who take it for the occasional evasion to get an engagement break to play the next big beatstick.

For me though, this card really shines in Calvin. Since he boosts both Strength and Agility in equal measure, a base skill value of 6 or higher is easily achievable even in the early scenarios of a campaign.

This card creates even more possibilities: In the Thick of It + Versatile +

Geared Up

Underworld Support

Short Supply

Forced Learning

Down the Rabbit Hole

This is the only chance to get these cards for every investigator because of “purchase at deck creation” text

The limits of Mandy's deck size just got a whole lot larger. Starting out with a 65 card deck is sure to make the other players at the table question how much horror you've taken. But combine it with two Versatiles to make a 75 card deck and the others will surely drive you to the asylum for the clear bout of insanity that you're experiencing. Then, combine that with Ancestral Knowledge to make a pseudo 80 card deck. What does one even put in an 80 card deck? Everything? At least the Dunwich encounter deck will lose much of its power. These combos would probably make activating Beyond the Veil an achievement in the most draw-heavy class but it would also make it a challenge to find the cards you need. Have fun shuffling this monstrosity! Combine it with the other new permanents for even more deck shenanigans.

An amazingly fun card, brings back vibes of Eldritch horror, having a suite of cool things your entire team has access to, really really crazy if you sit down with your team and come up with some combo's with it.

A side note is I cannot seem to add this card to decks, it doesn't show up in card lists when I am making a rogue deck and when I manually search for it no "add copies to deck" function is available, anyone else having this issue with this or any other cards?

EDIT: the issue seems to have been fixed now.