Loved how Wild Hunt's Bestiary (Witcher III) not only added lore and depth, but became a tool you'd pore over as a monster hunter. Subsequent encounters would add another paragraph or 2 and details on strengths and weaknesses. Also love the idea of having it done in an old school journal type format one of your more artistically inclined party members might have.. I'd even add a skull tally just to keep the record straight. Could be like your own in-game DnD Lorebook.
