Before each mystery, you gain one Advantage - something that prepared you for the challenge ahead. This could be training with your weapon, bonding with a companion, making a useful contact, or a meaningful experience that gives you confidence. Your Advantage can be used once per session to add +2 dice to a single skill test (or when pushing a roll). You must declare you're using your Advantage before rolling.
You can choose any skill as your Advantage - not just your main skill. Examples include: 'I trained with my rapier day and night,' 'A new contact seems to like me,' 'I was blessed by an angel,' or 'The conversation with [NPC] resolved our differences.' You can also gain Advantages by strengthening bonds with other player characters. After the mystery, your Advantage is lost and you must choose a new one for the next adventure.
Gaining an Advantage is an opportunity for roleplay. Instead of just declaring your bonus, you actually play out the scene where you're preparing. You might train your sword skills, study old texts in the library, visit a mentor, or have a meaningful conversation with a companion. This helps ground the mechanical bonus in the story and lets you develop your character further.