Read over the Priest's notebook

A player-created Guide is available for this content: Hearts' Game (Guide)

How are the above links here?

ID: 260804

Spoiler warning! This page contains details about Fallen London Actions.

From: Two of Briars: Snarl

He rarely leaves it unattended, but it might hold answers – or inspiration.

Game Instructions: This will give you a boon that enhances King accomplices, making them produce greater progress. If you already have the Ace of Kings, it will give you one Poisonous Preparation.

Success

Hearts' annals

The Priest employs [...] shorthand notation which is initially impenetrable. [...]you work out just how one encodes 'punched the target repeatedly until they became poisoned' in scant cursive [...]the book is open to you [...] a detailed almanac of the whole game.

•  You now have 1 x Ace of Kings
•  You've gained 1 x Hearts' Game: Exploits
•  Elusiveness of your Target is increasing… (+3 CP) (applied with probability based on Hearts' Game: Turns this Round) ^{What does this mean?}
•  Poison Tolerance of Your Target is increasing… (+2 CP) (applied with probability based on Hearts' Game: Turns this Round) ^{What does this mean?}
•  You've gained 1 x Hearts' Game: Turns this Round (hidden)

With Ace of Kings:

•  You've gained 1 x Poisonous Preparation