Scholar

Most scholars prefer to remain safe in the metaphorical "Ivory Tower" of academia, never far from the library or lecture hall— but not all. Whether by choice or necessity, certain well-educated experts with the hands-on skills of a rogue pursue field work alongside adventurers.
As an adventuring scholar, you use your expert knowledge for the benefit of allies, contributing well-researched lore on anything from the weaknesses of magical creatures to the construction of ancient tombs. Rogues like you are said to display a dedication to research, truth, and knowledge that can rival the higher calling of a cleric or paladin.

Close Observation

At 3rd level, when a creature misses you with an attack roll, or when you succeed on a saving throw a creature forced you to make, if you can see that creature, you can use your reaction to force it to make a Charisma saving throw against a DC equal 8 + your proficiency bonus + your Intelligence modifier. On a failure, and you immediately learn whether the creature has any damage immunities, resistances, or vulnerabilities and what they are. Whether or not the saving throw fails, you gain advantage on the next attack roll you make against that creature before the end of your next turn.

Scholarly Pursuit

At 3rd level, you choose one Scholarly Pursuit from the options listed at the end of this class description, granting you the listed benefits of the option selected. You gain one additional Scholarly Pursuit option at 9th level, 13th level, and 17th level.
In addition, you gain proficiency with your choice of either one tool or one of the following skills: Arcana, History, Investigation, Medicine, Nature, or Religion.

Flash of Genius

Starting at 9th level, your mastery of lore allows you to devise unexpected solutions under pressure. When you or another creature you can see within 30 feet of you makes an ability check or a saving throw, you can use your reaction to add a bonus to that roll. The bonus is equal to your Intelligence modifier (minimum 1). You can use this feature a number of times equal to your Intelligence modifier (minimum of once). You regain all expended uses when you finish a long rest.

Use Magic Device

By 13th level, you have learned enough about the workings of magic that you can improvise the use of items even when they are not intended for you. You ignore all class, race, and level requirements on the use of magic items.

Practiced Acuity

Starting at 17th level, whenever you have advantage on an ability check or attack roll that uses Dexterity, Intelligence, or Wisdom, you can reroll one of the dice once, provided the roll also lets you add your proficiency bonus.

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Scholarly Pursuits

Options for the Scholarly Pursuit feature are listed here in alphabetical order. You can never take the same Scholarly Pursuit option more than once, no matter how many times you get to select one, even if that Scholarly Pursuit offers different choices.
Academic Researcher. You gain a +2 bonus to all Intelligence checks, and while you are in a good library or well-equipped laboratory, you have advantage on all Intelligence and Wisdom checks that include your proficiency bonus.
Crafter. You gain proficiency with one tool of your choice, and you can grant temporary hit points to crafted objects. By spending 10 minutes using appropriate tools to work on an object or structure you can touch, you can make a DC 10 ability check with those tools. On a success, you grant that object (or a section of it equivalent to a 5-foot cube if it is larger than that) temporary hit points equal to your proficiency bonus + your level. In addition, whenever an object has been repaired, damaged, created, or destroyed with any kind of tool, you have advantage on all Intelligence and Wisdom checks to discern information about that object.
Diplomat. You gain proficiency in your choice of one of the following skills: Deception, Insight, Intimidation, Performance, or Persuasion. When you make an ability check with the chosen skill to influence or discern information about a creature that is indifferent or hostile towards you, you add double your proficiency bonus to the check instead of your normal proficiency bonus.
Expert. Choose one skill, tool, or vehicle with which you are proficient. You gain expertise with the selected proficiency, which means your proficiency bonus is doubled for any ability check you make that uses it.
Metaphysician. You gain proficiency in your choice of either the Arcana skill or the Religion skill, and you learn your choice of either two cantrips from the cleric spell list or two cantrips from the wizard spell list. Neither cantrip you choose can require a saving throw. In addition, you can also cast the comprehend languages spell as a ritual. Intelligence is your spellcasting ability for all these spells.
Physician. You gain proficiency in your choice of alchemist’s supplies, herbalist's kits, or the Medicine skill. As a bonus action, you can expend one use of a healer’s kit to cause a creature you can touch to regain 1 hit point. If you continue tending to the creature’s wounds for 1 minute while taking no other actions, you can make a DC 15 Wisdom (Medicine) check to allow the creature to spend Hit Dice to regain hit points, as if at the end of a short rest. The maximum number of Hit Dice a creature can spend in this way is equal to your proficiency bonus.
Student of Warfare. You have studied the arts of war and military strategy. You learn one Fighting Style of your choice from the fighter class. You can never learn the same Fighting Style more than once, no matter how many times you get to choose one.
Toxicologist. You are well-educated in the science of poisons: their creation, their effects, and their handling. You gain proficiency with poisoner’s kits. With one hour of work using a poisoner’s kit and expending 50 gp worth of materials, you can create a number of doses of potent poison equal to your proficiency bonus. Once applied, the poison retains potency for 1 minute, or until you hit with the weapon. When a weapon coated in this poison deals damage to a creature, that creature must succeed on a Constitution saving throw (DC equals 8 + your proficiency bonus + your Intelligence modifier). On a failure, the creature takes poison damage equal to half your rogue level + your Intelligence modifier (minimum 1) and is poisoned for 1 minute.