Realm of Death

My take on this set: These cards are terrifying. Both of them have the same effect: Forcing additional triggers out of Haunted abilities. These come in many shapes and forms, and only few of them are no big deal.
Haunted abilities range from some lost resources over gaining some points of damage/horror or having to discard assets to losing actions or even throwing doom around. Seeing these trigger every turn due to Realm of Torment or getting a “free” slap in the face from a surging Shapes in the Mist is never good.
Note that these will not only trigger the Haunted ability on your spectral locations, but also any additional ones from sources such as Wraith or Nether Mist.
That these cards are used in half of the scenarios of Circle Undone doesn’t make them easier to swallow either. I have the highest respect for the Realm of Death set.

What it does: Realm of Torment is put into a player’s threat area. While there, the affected investigator has to resolve all haunted abilities at their location, including ones that are added to the location from other sources. At the end of each of their turns, the investigator has one chance to discard the card by passing a Willpower test.

My take: It’s Frozen in Fear, but worse. There, i said it. Frozen in Fear makes players conditionally lose an action, this thing can do all sorts of shenanigans. A player that can’t get rid of Frozen in Fear is slowed down, someone who is stuck with Realm of Torment might just die to it. A frustrating card that already does as much as most other treacheries on its first activation and only ramps up from there.

Threat level: High to Very High. Can be an absolute show-stopper, but the Willpower test at least allows fighting against it.

Dealing with it: Can i talk to you about our lord and savior, Alter Fate? Or its prophet, Logical Reasoning? Seriously though, all of the Circle Undone wants players to have high Willpower or face the consequences. Anyone who is not able to reliably pass Will(3) tests to shake off cards like this one or any of the Hexes, will need to have a backup plan like one of the cards mentioned. If you are stuck with one of these, you can somewhat control the effect you have to deal with by choosing where to end your turn. But doing so is of course going to eat up actions like crazy.

What it does: Shapes in the Mist triggers the haunted abilities on your location, then surges into the next encounter card in line.

My take: Surge on a relevant card is such a pain. Haunted abilities can be quite powerful, getting one of them on top of what the encounter deck had planned for you anyways feels just bad. A very unpredictable card that sometimes does little, but any effect at all is already enough when Surge is involved.

Threat level: High. Relevant effects with Surge are power spikes on top of the generally already fairly high level of the Circle Undone campaign.

Dealing with it: In theory, one could try and be mindful of where they end their turn when there’s four cards in the encounter deck that care about it. In practice, this is usually not possible or reasonable. This is a card where you just grin and bear it.

Return to Circle Undone: Unstable Realm

My take on this set: This replaces a very impactful set of cards that are notably difficult to interact with, instead offering two toned down versions. I like this replacement set. Unstable Energies is a cool design that ensures additional haunted triggers without being too punishing for low willpower investigators. And From the Other Side feels like a less infuriating version of Shapes to me. Reducing the amount of surging is a good thing in my opinion.
Unstable Realm removes the treachery with the dreaded Frozen in Fear template from the game, which is something to be happy about. However, it should be noted that the replacement for Trapped Spirits introduces a new one where there wasn’t one before. So some of the power of this set merely wandered over to that other set.
Unstable Realm is also a good set to mix with the old one. Using one copy of each of these cards for a combined set should work very well.

What it does: Unstable Energies attaches to the investigators location and is discarded only if at the end of the round no investigator is still at the location. Each investigator (not only the one that drew the card) that leaves the location will have to resolve each haunted abilities there.

My take: A very interesting card that can potentially hit multiple investigators if they shared their location during the Mythos phase or if they are forced to walk through the location while the treachery is still up. This replaces Realm of Torment as a way to get multiple Haunted triggers out of one encounter card, but spreads them across the team. It’s net impact is going to be similar to the card it replaces, but without the potential of pummeling one player forever.

Threat level: Mid. Depending on the Haunted effect of the attached location, this can be a roadblock that stops players unwilling to deal with it from moving through that location.

Dealing with it: Unless cancels or Alter Fate are involved, this will always trigger at least once. How to deal with the card’s effect is obviously going to depend a lot on the actual haunted ability on the location and on how many people are impacted by it. Small groups will find this card a lot more lenient than Realm of Torment.

What it does: After failing an agility test, the player has to resolve the haunted abilities of their current location. Should they fail by 3 (which is also the difficulty), the haunted abilities are resolved an extra time.

My take: Oh thank god, Shapes in the Mist’s reign of terror is finally over. Its replacement, From the Other Side, threatens to resolve the haunted effect twice, but for one there is a skill test involved that can possibly prevent it in full. Secondly, there is no contingency for situations where there are no haunted abilities on the location. The card is just a freebie then. Finally, and most importantly, there is no Surge anywhere on the card. This is one of those few cases where a replacement is significantly weaker than the original but i am fully okay with it because the original was just such a pain.

Threat level: Low to Mid. Certain haunted effects can be brutal if you have to trigger them twice, but that worst case is not all that likely.

Dealing with it: Is it worth thinking about where to end your turn just because of two copies of this card in the encounter deck? Probably not. Like Shapes in the Mist, this is probably something you will have to deal with unprepared most of the time, but at least you get a fighting chance through the agility test now. Even if your agility is low and you’ll likely fail, consider pitching an icon or two if you have them if you think that can prevent the “fail by 3” clause from becoming active.