The Witcher: A Witchers Journal
The Witcher: A Witchers Journal - Rules of Play says:
A Witcher’s Journal is a supplement for The Witcher TRPG which gives you a number of new monsters and intriguing plot hooks to use in your game as well as new lore and an in-depth investigation system. Alongside these new monsters, the in-depth Investigation System provides a framework for your group to experience mysteries. Rather than just relying on the players to deduce the truth, or risking a crucial clue being missed due to a failed skill roll, this system treats the mystery as its own kind of monster to be defeated. Find clues to overcome the mystery, while avoiding the obstacles which distract your focus from it. Usable for any kind of mystery, not just an unknown creature, the Investigation System is a valuable new tool for any Witcher GM.