Dark Veiling

My take on this set: A set that interacts with concealed enemies, without providing any of its own. Instead it will come together with Crimson Conspiracy, Cleanup Crew or both. Both cards in here are reasonably impactful. They share their ability to tax the players actions or their stamina/sanity and both give the player the option to decide on what is more important to them right now: Staying alive or being able to act.
I think these are fine cards, but nothing too out of the ordinary.

What it does: Seeing Shadows stays in the players threat area until it is discarded through the use of two actions, very similar to many weaknesses. While active, the investigator affected by the card takes a horror whenever they fail a test at a location with a face-down mini card.

My take: In the scenarios that use this set, concealed enemies are usually going to be plentiful. And even when they aren’t, the locations with concealed enemies are usually the places to be to either advance the scenario or just to deal with those enemies. As a result, this is for the most part a straight copy of Atychiphobia.
For many investigators, this is not really feasible to keep on the board for long as the horror can start to stack up quick by itself … and there’s a good amount of other horror sources around in this campaign as well. If you are playing someone like Winifred or Mark who do really well at testing, you might be tempted to keep Seeing Shadows around, but that can easily backfire at some point too.

Threat level: Mid. Depending on the investigator this card can have some impact, but at least it comes with a built in ability to get rid of it.

Dealing with it: It’ll probably be rather obvious to you whether this needs dealing with or not, so you can assess whether to make use of that two action discard. Remember that in multiplayer any player can use those actions to help the one who drew this card out.
Seeing Shadows doesn’t have an effect while at a location without concealed cards, but that is unlikely to consistently be of much help. It might allow you to keep the card around for a turn or two longer, though.

What it does: The player has to choose: Either each concealed enemy attacks that player… or each player loses an action. The card has Peril, so other players do not get a say in this decision. Should no concealed enemies be in play, Figures in the Dark surges.

My take: This card scales wildly in different directions, making it incredibly inconsistent in how impactful it is. The first option scales with the count of enemies in the shadows. If it’s only one, this will often just deal a damage or a horror which isn’t too much of a deal. But in some cases, there’s going to be several concealed enemies around, making the first option hurt quite a bit. The second option however scales with player count. Playing true solo, this takes one action away, which is expected and fine for an encounter card. But on the upper end, it costs three or four actions, for the equivalent of one player’s full turn or more. That’s going to be a hard pill to swallow. Even just at two players, having to pay two actions isn’t great. Scarlet Keys taxes actions a lot and due to impacting everyone, this has a high chance of stacking up with something else that eats up actions… like Seeing Shadows, for example. Or just the concealment mechanic is general.
It should be noted that high player count also leads to a higher enemy count, so full parties will have both options scale higher than smaller groups.
With both of the options able to scale rather hard towards either being fine or awful, Figures in the Dark is often not going to offer much of a choice at all, with an obvious pick between the two.

Threat level: Mid to High. This card can occasionally be tame, but the high amount of scaling involved is to be respected. Low in Solo, where losing an action is always available as a reasonable option.

Dealing with it: In bigger groups, this card is a good argument for staying on top of your concealed enemies and working aggressively on rooting out whatever spawned in the shadows. The goal is being able to pick the first option without feeling terrible about it. Of course, this can also be achieved by having healing or soak in excess available (which is a good idea for Scarlet Keys anyways).