Beast Researcher are, like the name suggests, folk who travel the world in order to study and catalogue all sorts of different creatures - whether simple forest critters, horrible undead or mighty dragons. They might be doing it for their own satisfaction - wanting to become a famous zoologist, or to teach others how to approach and deal with such creatures in a safe and efficient manner.

Field Studies

Beginning at 3rd level when you choose this archetype, you’ve begun your journey as a researcher of all manners of beasts, whether magical or not. You gain proficiency with the Wisdom (Survival) and Wisdom (Animal Handling) skills. Additionally you gain the following feature:

Bestiary. You have a special record containing all of the knowledge you have gained about creatures you have encountered and studied, referred to as a Bestiary. The Bestiary can have whatever form you wish, such as a leather bound tome, a stone tablet covered in runes or a messy collection of parchment. You have advantage on Wisdom (Survival) checks to track creatures you have studied and added to your Bestiary, as well as on Intelligence ability checks to recall information about them. Additionally, after studying a creature and adding it to your Bestiary, you learn of any resistances, immunities or vulnerabilities it might have.

To add a creature to your Bestiary, you must fulfill any of the following requirements:

• You must have studied the creature out of combat for 1 hour while remaining completely uninterrupted for the duration.
• You must have spent a long rest reading and studying a text that comprehensively details the creature. The DM determines if the text has sufficient information.
• You must have participated in the killing or capturing of the creature. You can then add it to your Bestiary at the end of a long rest.

To add a creature to your Bestiary, it also cannot have the humanoid or construct creature type.

If your Bestiary is destroyed or you happen to lose it, you can create a new one by spending 8 hours and 50 gp worth of materials.

Benefit of Knowledge

At 7th level, your extensive studies of the creatures detailed within your Bestiary has given you insights into how to better deal with them in combat. While fighting a creature detailed in your Bestiary, you can grant yourself any of the following benefits:

Studied Aim. You can add your Wisdom modifier to any attack roll you make against a creature detailed in your Bestiary.

Studied Strike. When you hit a creature detailed in your Bestiary with a weapon attack, you can choose to deal an extra 1d6 damage to it. This extra damage increases to 1d8 damage at 11th level, and 1d10 at 15th level.

Studied Dodge. You can grant yourself advantage on a saving throw you make against a creature detailed in your Bestiary.

You can use this feature a number of times equal to your Wisdom modifier per long rest.

Seasoned Researcher

At 11th level, you’re a well-traveled and experienced researcher. Your speed increases by 10 feet, and you ignore the effects of difficult terrain caused by non-magical terrain. Additionally, you gain the following feature:

Improvised Communication. Your research of various creatures has given you insights into different forms of communication. After spending 1 minute with a creature, you can communicate basic thoughts and ideas to it and have a basic understanding of what it might be saying back, even if you do not share a language. If the creature you’re attempting to communicate with is detailed in your Bestiary, you have advantage on any Charisma checks you make to influence it, and on Wisdom (Insight) checks you make to understand it.

Zoological Prodigy

At 15th level, you’ve practically become a walking Bestiary yourself, and are unrivaled by but a handful in your vast knowledge and understanding of the creatures that live in your world. You gain the following features:

Quick Study. You have enough experience studying creatures that you can often make assumptions and determinations about their abilities on the fly. As an action, you can choose one creature within 60 feet of you. That creature must make a Charisma (Deception) check against your Wisdom (Insight) check. If you succeed, you can treat the creature as if it was detailed in your Bestiary for 1 minute. You can use this feature a number of times equal to your Wisdom modifier per long rest.

Researched Mimicry. Your studies into the creatures detailed in your Bestiary has given you insight into how to use magic to take their forms. You learn the Polymorph spell, and can cast it once per long rest without requiring a spell slot or material components. When you cast Polymorph in this way, you can only take the forms of creatures detailed in your Bestiary.