Merging Realities

My take on this set: There are some cards in this set that look flashy at first glance but ultimately these cards don’t have a particularly great impact. All of them can be mitigated fairly well by coordinating with teammates. And in the case of Night Terrors, the effect itself isn’t actually bad enough for most investigators/decks that you’d want to spend an action on it.
What that leaves us with is a set of three cards with wildly different effects that also don’t play much into the two scenarios it is used in. It’s some inoffensive filler that bolsters up the numbers in the encounter deck and acts as a bit of relief from whatever other cards make up that deck. That is perfectly fine but nothing to get overly excited about.

What it does: Night Terrors lingers in a players threat area until they decide to discard it. While affected, the investigator has to reveal the top three cards of their deck every time they fail a test. Each weakness revealed this way is drawn, the other cards are removed from game.
To get rid of this card, the player has to spend an action and take a somewhat difficult willpower test. Night Terrors is discarded no matter if the test fails or passes.

My take: Looks much worse than it really is. This treachery is one of the very few that actually removes cards from the game instead of just discarding them and that makes it look quite scary. However, this is only a minor difference for most investigators. Unless playing an investigator that depends on some key copies of their cards (for example because they want to assemble the Pendant or Three Aces), losing a few cards from the deck doesn’t matter a whole lot. Drawing the weakness is even borderline benefitial as drawing the card that way doesn’t replace one of the natural draws from the upkeep phase. So unless you plan on failing enough tests that this would completely decimate your deck, you can probably ride it out safely.

Threat level: Low. It only has minor impact, except for a few choice investigators that depend on certain cards to function at all.

Dealing with it: If drawn in the the first few turns of the game, it can potentially lead to shredding a good part of the deck if the player fails a lot of tests during the scenario. In that case, spending the action is worth it. Otherwise it depends on the investigator this can just stay in play and do its thing or if the action needs to be spent. In any case, it’s likely not going to an urgent thing to do.

What it does: While Glimpse of the Underworld is in a players threat area, they take an additional damage or horror whenever they would take some. To discard the card, the player can take one damage and one horror as a free trigger on their turn, no action required.

My take: Just take the damage and horror and be done with it. Unless you are in your last two turns (or one damage/horror away from defeat), there is little sense to having this stick around and potentially cause extra harm.

Threat level: Low. This mostly just deals a point of damage and horror. In multiplayer you sometimes even get to choose who takes it.

Dealing with it: Remember that any player at the same location can activate this card’s free trigger ability. So even if the one who got stuck with Glimpse is low enough on stamina and/or sanity that discarding it would be an issue and without any assets to soak it, then a teammate can discard it for them.

What it does: Unlike the other two cards from this set, Threads of Reality doesn’t go into the threat area. Instead, it attaches to the most expensive asset the player has in play and while there, blanks the textbox of that asset.
To discard Threads and re-enable the asset, an investigator at that location has so spend an action and sacrifice another asset.

My take: This card can be a nuisance as it does cost an action and an asset. There is some player choice here in which asset to sacrifice for the effect, but no test to completely avoid it like on many other cards like it. Despite the lack of a saving throw, Threads is usually less impactful as for example the Core Sets’s Crypt Chill or Forgotten Age’s Lost in Time. To protect against the other two, players usually use low cost assets that can be discarded to protect the important cards. With Threads, you can play those low cost assets even after getting hit by the treachery, so your first turn Leo de Luca or .45 Thompson is relatively safe.

Threat level: Mid. It does cost the player an asset and an action, but isn’t able to outright destroy a card permanently. The final say in what goes to the discard pile lies with the player.

Dealing with it: Like with the two other cards from this set, anyone at the same location can pitch in to get rid of the treachery provided they have a spare asset to discard. Use that to minimize the inconvenience caused by this card.