Prerequisite - Must have at least one level in the Rogue class

Through thorough research during a short or long rest (given you have a text or other character expertly informed), you are an expert when it comes to a type of creature (beast, monstrosity,..etc) or humanoid race’s anatomy, and you exploit that knowledge to the best of your abilities. You gain the following benefits:

• You gain proficiency in the Medicine skill.
• Choose a type of creature or humanoid race. When you use the Sneak Attack feature against that creature, the damage dice from the extra damage increases from d6 to d8.
• The knowledge of the creature or race lasts until you decide to change your focus to a different subject during another short or long rest