Bestiary

 Prerequisite: Intelligence of 11 or higher

You are a specialist in observation and learning of the creatures you have fought and slain, able to pick up on weaknesses and make note of them when in the heat of battle, remembering this for later reference. You gain the following benefits:

• Increase your Intelligence score by 1, to a maximum of 20.
• Whenever a creature dies within 60 feet of you, you can use your reaction to make an Intelligence (investigation) check, the DC equalling 10 + the creature’s Challenge Rating. On a success, you gain 1 point of Expertise in that creature. 
• For every point of expertise you gain for a single creature type, you gain a permanent +1 to attack rolls against them and to Intelligence checks made if pertinent to that creature. You can have a maximum of Expertise points for each creature equal to your Intelligence modifier.