I got this card in my recent campaign as Minh Thi Phan, and it was awesome. Playing it with Scavenging (2) you can basically convert 1 resource into 2 cards. It can even be the resource you just got from Dr. Milan on the same test, because both abilities trigger at the same time. Then use Pantalone to punch some Rats, pick a Locked Door, evade an enemy or just discard the card to a treachery like Crypt Chill. Rinse repeat on the next test with Deduction (2), Perception (2), Sharp Vision, Archaic Glyphs: Guiding Stones...

Try it out before the next Taboo list will remove this card from the game after use!

Q: When no more set-aside Monster enemies left, can I trigger action ability on this card to discard?

RR "Target" says :

The term "choose" indicates that one or more targets must be chosen in order for an ability to resolve. The player resolving the ability must choose a game element (usually a card) that meets the targeting requirements of the ability.

If an ability requires the choosing of a target, and there is no valid target (or not enough valid targets), the ability cannot be initiated.

This card has an unexpected synergy for an investigator who came out years earlier. Jim Culver, musician, can use this spell to great effect. His power lets him to treat the elder sign as a skull, and skulls as +0. But that’s different than the token.

So when Jim puts Flame into play, he’s only afraid if he draws an actual zero (on hard or expert, there aren’t any +1s in the bag.)

This makes it much better for him than shriveling, which can trigger off during a skull token even if it counts as a zero.

LivefromBenefitSt's review of the first Law of this set pretty much sums up why this might be the most annoying Treacheries in the game.

Fun fact for this particular card is that, if I'm not mistaken, this is the first instance of an effect that fundamentally changes the game depending on the language you are playing (card titles differ in word length in different languages). So for example Look what I found! is playable while you hold Pandemonium and can be discarded to get rid of it if you are playing the game in English; while it's the opposite (dead card in hand) if you are playing in Spanish ("¡Mira lo que he encontrado!").

This is a question as opposed to a review: suppose an investigator controlled the custodian and then lost control of it in Act 3a. Then for the purpose of Act 2b (and the scenario resolution), is it true that the investigator "has performed" the "An investigator controls the Custodian?"

To be clear, I think this is different from Act 2a, where it states "if three of the following are true..." and when you lose control, it is no longer true that you "have control". However, given the way the game resolves the number of tasks in the resolution of the scenario, it seems it expects the number of tasks you have "performed by the time the scenario ends" (as opposed to, say "to be true by the time the scenario ends") to be definitely between 3 and 6, and you can get into a state where you only have 2 tasks (by doing the Custodian and 2 other tasks, then losing the custodian), which is not given a consequence in the resolution.