You decided to dedicate your life to the observation of beasts, magical creatures and animals likewise. While walking down the path of a Beast Researcher you learn to duplicate a beasts behavior and gain some of their abilities.

Study

At 3rd Level, you can use one spell slot of any Level and choose to study a creature by following it for 10 minutes. You have expertise on stealth and perception during this time. If you loose sight of the creature you loose the boni and have to start again. If you weren't detected by the creature after the duration ends, you learn everything the creature knows about this environment and it's own group. If you follow a wolf for example, you can learn the routes a wolf chooses for it's hunt, where his lair is, how many wolves are in his pack and which other kinds of creatures live in this environment.

Basic Research

At 3rd Level, you have conducted your first research on a creature and can now modify your body through magic. 

You gain one of the following features of your choice, depending on the creature you decided to conduct your first research on:

Dragon scales

(Dragon) You have watched many attacks, that bounced off a dragon's scales, which gave you the idea to grow them too. There are tiny, dragonic scales all over your body. When you aren't wearing armar, your AC equals 13 +your Dexterity modifier. Works with the Defense Feat. 

Spider climb

(Monstrosity) Watching huge spiders like the Ettercap surprising their oponents from above, you decided to try it out yourself. Little hooks, that are undetectable by the bare eye grow on your hands. You gain a climbing speed equal to your walking speed. You can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check. 

Telepathic Shroud

(Abberation) Your research on weird monster you can't even classify, has allowed you to understand a little how their brain works, which allowed you to modify your own. You are immune to any effect that would sense your emotions or read your thoughts, as well as all divination spells. Additionally you gain a 30 ft Telepathy, that you can only use to communicate with creatures, that have agreed to it before hand.

Intermediate Research

At 7th level, you have conducted your next research and can thus magically modify your body even further

You can either choose a feat, that you haven't yet chosen from Beginner's Research or choose one of the following feats.

Elemental Form

(Elemental) You have seen the elementals use their form to their advantage and have learned to polymorph yourself into the form of an element. As a Bonus action, you can decide on one of the following creatures: Air Elemental, Earth Elemental, Fire Elemental or Water Elemental. For the duration of 10 minutes you can copy all of the chosen monster's feats. (This doesn't include any Actions, but includes it's feats damage immunities, resistances and vulnerabilities, as well as their senses, speeds and condition immunities.)

Oozification

(Ooze) You watched weird slimes dissolve armors and humans with a mere touch. You modified your body to polymorph into ooze, that melts any not magical items made of metal or wood by touching it. You can also choose to use your action to attack with an ooze hand.

Pseudopod. Melee Weapon Attack: +proficiency bonus +dexterity modifier to hit, reach 5 ft., one target. Hit: 1 natural attack plus (2d8) acid damage. In addition, non magical armor worn by the target is partly dissolved and takes a permanent and cumulative -1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10. If a creature is reduced to 0 hitpoints by this attack it dissolves andinstantly dies without rolling any death saving throws.

The acid damage of Pseudopod becomes 3d8 on 11th Level, 4d8 on 15th Level and 5d8 on 20th Level.

Wild Attacks

(Beasts) You have seen multiple animals fight like mad beasts and researched on their claws and teeth, which allowed you to copy their fighting styles and modify your body to fit those styles. You gain the following natural weapons and the Multiattack feature:

Claws. Melee Weapon Attack: ++proficiency bonus +strength- or dexteritymodifier to hit, reach 5 ft., one target. Hit: 11 (1d6 +strength- or dexteritymodifier) slashing damage. 

Bite. Melee Weapon Attack: +proficiency bonus +strength- or dexteritymodifier to hit, reach 5 ft., one target. Hit: 11 (1d6 +strength- or dexteritymodifier) piercing damage. 

Multiattack. You make two attacks: one with your bite and one with your claw. You can use your bonus action to make a second attack with claw. If you have another weapon in your second hand you have to attack with that weapon instead.

After the 11th Level your natural weapons are considered magical if they have to overcome resistances or immunities. 

Legendary Research

At 11th level, you managed to decipher one of the many wonders of magical beasts. The ability to change fate every legendary creature possesses is now in your hands.

Legendary Resistance. If you fail a saving throw, you can choose to succeed instead.

You gain one use of Legendary Resistance at Level 11 and 2 at Level 15

Final Research

At 15th level, you managed to study a legendary kind of beast, your magnum opus to say the least. You can choose one of the feats of Begginer's Research or Intermediate Research, that you don't know yet, or one of the following feats.

 

Ascension

(Celestial) You have studied a variety of myths and legends and even saw a celestial with your bare Eye. Your mind is now synced with the way of thinking a celestial possesses. You gain a resistance against radiant damage and the following feats.

Magical Resistance. You have an advantage on saving throws against spells and other magical effects.

Angelic Weapon. All of your mellee attacks and ranged weapon attacks deal an extra 3d8 radiant damage.

Healing Touch. If you touch a creature you can magically heal it. You can heal 10 +the amount of your Level in ranger doubled hitpoints. This pool of hitpoints gets recharged after completing a long rest.

 

Pandemonium

(Fiend) You studied the Demons and Devils of this world and combine the best of both in yourself. You gain a resistance against poison damage, a dark vision of 60 ft. and the following feats.

Magical Resistance. You have advantage on saving throws against spells and other magical effects.

Devil's Sight. Magical darkness doesn't impede the imp's darkvision. 

Teleport. You can magically teleport, along with any equipment it is wearing or carrying, up to 120 feet to an unoccupied space it can see. You have 2 uses of Teleport and you regain those uses after 1 short rest.

Secret of the Undead

(Undead) After seeing an army of undead eternally regenerating and not dying, you discovered their secret of immortality and used it on yourself. You are now considered an undead humanoid creature. You gain an immunity against poison adamage, the condition poisoned and exhaustion, as well as the following feats.

Undead Fortitude. If damage reduces you to 0 hit points, you must make a Constitution saving throw with a DC of 5 +the damage taken, unless the damage is radiant or from a critical hit. On a success, you drop to 1 hit point instead. 

Turn Resistance. You have advantage on the effects of turn undead.

Undead Nature. You don't need to breath air, drink water or eat food to survive.