INTRODUCTION

The Rules Reference establishes that in standalone mode winning a scenario occurs when you complete a resolution on an Act card. Doing this in just one turn, before even letting the game advance to the very first enemy phase, should be impossible, but due to an oversight in a specific scenario this is actually achievable, while using the taboo list and without any infinity shenanigans.

This deck is more of a proof of concept than anything actually practical, it's designed to maximize the chances of achieving this extraordinary feat by providing several alternatives that can be available on the opening hand.

The exploitable scenario is "Where Doom Awaits", or more precisely "Return to Where Doom Awaits". In an attempt to fix an unfair mechanic against investigators with low intellect, the designers decided to rework Base of the Hill and Ascending Path so that instead of passing a specific investigate action on those locations you need to discover clues on them; that allows for several different strategies to become available for the task. The idea here is that as soon as you discover a clue from there, the clue is immediately spent and a location is spawned, this is done through a forced ability.

THE EXPLOIT

Enter Read the Signs, a card that allows you to investigate a location while ignoring any effect and keyword on it. This of course includes Forced effects. In fact this card was very deliberately designed to ignore forced effects, just not this specific forced effect. In other words by using Read the Signs on both the return to version of Base of the Hill and Ascending Path you can basically bypass the entire mechanic of the scenario.

Here's the plan to beat the scenario:

1. Investigate Base of the Hill using Read the Sign to discover 2 clues from it and ignoring its Forced ability. The 2 clues must be immediately spent to advance, as stated on the Act card itself. This reveals Ascending Path, making it accessible.
2. Move to Ascending Path
3. Investigate Ascending Path using another copy of Read the Sign to discover 2 clues from it and ignoring its Forced ability.
4. Move to Sentinel Peak spending the 2 clues just gained. This Advances the Act.
5. Discover 2 clues from Sentinel Peak (with Drawn to the Flame or Intel Report). This makes it possible to advance the final Act that leads to R1.

This requires 5 actions (so 2 extra actions) or some way to move without spending any. This also could potentially require more than 5 starting resources and to make things more likely to happen something to search for the right cards or an ability to have more than 5 cards in the starting hand. Guess who can have all those requisites...

THE DECK

Sefina Rousseau would be the perfect candidate for this task simply by virtue of the fact that she has access to both mystic cards (required for Read the Signs) and Rogue cards (which offer several ways to get more resources and extra actions). But Sefina is even better because she can start with 8 cards in hand and she can choose from 13 (which is more than what you would see with a mulligan). But that doesn't even end here. Whereas any other investigator would be required to have both copies of Read the Sign in hand for this to work, Sefina has a backup plan in the form of The Painted World. Even if she gets a single Read the Sign, she could still execute the plan by placing it beneath her investigator card and copying it with two of her signature cards.

Getting the last clues

As for the final location Drawn to the Flame or Intel Report can both do the job, and between the 2 there's 4 cards available in the deck. Pilfer can be used as a last resort. Of course this will provoke an attack of opportunity from Seth Bishop, but that's hardly an issue. Drawn to the Flame is the ideal card, there isn't really anything in the encounter deck that has the potential to thwart the plan. Otherwise Intel Report should be used, but that introduces the issue of available resources.

Solving the resource issue

Since two copies of Read the Sign must be played, 4 resources must be spent just for those. This would leave only 1 resource available, which is not enough to play Intel Report. This is why this deck includes two copies of Another Day, Another Dollar, bringing the initial resources amount from 5 to 9. However the plan might require even more resources to be spent, so two copies of Uncage the Soul are included so to allow playing Read the Sign at no cost.

Gaining those extra actions

Ideally the initial hand should include one copy of Anna Kaslow and one of Ace of Rods (Funny how these cards that are usually not very good, are in fact the absolute best in this case). With Anna Kaslow you can immediately search and put into play a copy of Ace of Rods while also increasing the tarot slots allowing for a second one to be put into play. This would cost zero resources and zero actions due to their abilities. So Ace of Rods is extremely good here, not just because it grants an extra action, but because it increases all skills by 2. This means that just with that Sefina can investigate using Read the Sign with a modified skill value of 10, which is enough to ensure success on anything other than the .

The second best option to gain an extra resource is Quick Thinking. It doesn't cost anything, and you can just commit it to the investigate test you must do anyway with Read the Signs. This requires the test to succeed by 2 or more, which has a chance of failing, but the deck also includes various cards that can be committed to increase those odds.

Finally the deck includes two copies of Swift Reflexes and Elusive. These cards can be played during any player window, but they cost 2 resources each, this requires that you either have Drawn to the Flame to use or Uncage the Soul. Elusive doesn't actually grant an extra action but it can be used to move for free. Ironically this card would be completely useless in this situation if this deck didn't use the taboo list.

Improving the odds

Even considering the amount of backup plans, there are still very good chances that the opening hand will not include all the necessary combinations of cards. This is why this deck includes two copies of Black Market. This costs an extra resource, but it should be fine in most cases. Having 5 extra cards available, on top of the initial choice of 13, covers more than half of the deck. Should that fail to or be unavailable, the decks also includes 2 thoroughly upgraded Friends in Low Places. This allows to search the top 9 cards of the deck for a spell card, which could be Read the Signs but also The Painted World.

FINAL TIPS

If the opening hand only provides one Read the Signs without any The Painted World, you should just keep the card in hand, your only hope at that point would be to find the other Read the Signs as a single copy of The Painted World wouldn't change anything. Of course this can change if you feel like you can get 6 actions allowing you to retrieve Read the Signs. If you have a Read the Signs and at least one The Painted World, then Read the Signs should be placed beneath Sefina's card. That way either another Read the Sign or another The Painted World would do the job. There isn't really any point in placing other cards beneath Sefina for the purpose of this plan. Several cards exist in this deck for no other purpose but to be committed to skill tests. Eldritch Inspiration might seem out of place, but it's 2 intellect icons, and that's why it's there. Initially this deck included Perception and other cards with card draw effects, but then I decided to eliminate them all. As per Standalone Rules this deck requires 3 Random Basic Weaknesses to be added. Some card draw isn't really worth the risk of drawing Paranoia or Amnesia. Of course not all of the cards included in this deck are necessary. If you want to experience the satisfaction of beating a scenario in 1 turn (perhaps as a revenge for getting defeated on the very first Mythos Phase), you don't need all those expansions. You could try without Black Market or Friends in Low Places, it would just require several attempts before you get a workable opening hand.