- Q: What happens to Call of the Unknown if there is no 'location other than your location' in play at the beginning of your turn? A: Nothing would happen. You would not shuffle it into your deck and take 2 horror; it would simply remain in your threat area. In other words, the condition of "f you did not successfully investigate the chosen location this turn" is not met because there was no chosen location.
Revelation - Put Call of the Unknown into play in your threat area.
Forced - At the beginning of your turn: Choose a location other than your location. When your turn ends, if you did not successfully investigate the chosen location this turn, take 2 horror and shuffle Call of the Unknown back into your deck.
Unless it's the back end of a scenario, you're going to end up tanking the 2 horror at some point. It's usually too much tempo loss to constantly move and investigate, even for Ursula. And once you take that 2 horror, you can look forward to drawing this again. Really that's what you're trying to prevent by satisfying that Forced trigger every turn- card draw denial. It is incredibly annoying to top deck this several times in once scenario. That said, take Mr. "Rook" to soften the blow. Yes, the card will recur even after Rook takes the two horror, but at least you pulled two other cards while drawing this one. It's a very thematic and engaging weakness to play around. Just take care you don't get hit too many times.
A delightfully flavorful signature Weakness. Looking at the two elements, the effect and the discard condition, we get:
The effect: This only punishes Ursula if she doesn't do what she loves to do. Good counter-cards to this are Pathfinder, Fieldwork, and, in a pinch, Shortcut. Either of the Esoteric Atlases or The Truth Beckons can also help, along with the usual suite of tools for boosting investigate tests. Seeking Answers can let you target a low-Shroud (or empty) location and still grab clues. As the difficulty level goes up, failure becomes more likely, so Ursula may pack some horror-soak allies, maybe an Art Student or, if you are using an Atlas, the Eldritch Sophist, or invest in some Logical Reasoning.
The discard condition: You don't. You either keep moving and succeeding at investigations (note testless clue-getting won't help; you have to investigate (although you can do it at a location with no clues)), or you take 2 horror and shuffle it back into your deck to strike again. Ursula doesn't really favor a high-draw strategy.
Taken together, this is a below average signature weakness, maybe average in a scenario with a cramped map and a lot of enemies or at high difficulties.
Just play Ursula and found this Weakness is never discarded. So I need to move and investigate every turn since I draw it around mid-game. Then I found some card to include for mitigate your tempo
Oh boy. I just finished a campaign of TFA as Ursula Downs
First off, the good stuff. The flavor on this card is right on. Like many investigator weakness, it slows down or counteracts what your character is good at, and I feel like 2 horror is a reasonable penalty for failing to satisfy the call. This would be a pretty light penalty except....
The bad stuff. When you fail, you shuffle this card right back into your deck. On average, you'll draw this maybe once or twice a scenario and eat 0-4 horror. I had a few cases where I thought "tempo is more important than 2 horror, I'll just tank it" and draw the card again within a few turns. In other cases I drew or a -5 token and botched the investigate check. This led me to quickly nickname Dr. Elli Horowitz "Dr. Horror-soak". This is all well and good for a rough weakness, except....
The worst stuff. Spoilers for The City of Archives ahead. The fact that this scenario is part of the same campaign where Ursula debuted is a kick in the nuts! Not only are you stuck taking 2 actions to move and investigate, you still have to pass the investigation check with your measly 2 . They were at least fortunate enough to have Lost Humanity as part of the encounter set, unless like me you were unlucky enough to not remove Call of the Unknown from the game. Then you become left with a really small deck where you either keep paying 2 actions or keep taking 2 horror in quick succession. The only saving grace here is that Towers of Pnakotus exists to beef your deck back up, but even still, you want to be drawing lots of cards in this scenario. The Call will find you soon enough.
Ultimately, all I would want is some (reasonable) way to get rid of this card for good. Maybe something like "When you succeed on this investigation check for the first time in a round, place a resource on Call of the Unknown. Then if there are 3 or more resources on this card, discard it".