The Knowledge-Seeker

 

Hellish Acumen

Beginning at 1st level, you are able to momentarily call upon a small fraction of your patrons vast knowledge. A number of times per Long Rest equal to your Intelligence Modifier, you may add 1d4 to any Intelligence, Wisdom, or Charisma Skill Check or Saving Throw. This may be done after the roll is made, but before the DM determines the outcome of the check. This bonus increases to 1d6 at 5th Level, 1d8 at 11th Level, and 1d10 at 17th Level. Your Spellcasting Ability is now Intelligence instead of Charisma.

Infernal Analysis

At first level, you are able to cast the spell Identify as a Ritual, even if you are not otherwise able to perform Rituals.

Library of the Mind

Beginning at 6th level, you may use your Action to manifest a portal that leads to an extradimensional space, no larger than 50 square feet, that contains all your personal knowledge within it's myriad of different books. You can make this space look however you want, so long as it resembles some kind of library; from a small study to an ornate scriptorium. You may choose to lock any number of books inside a locked space, which cannot be opened short of a Wish spell, or if the creator of the Library allows it to be opened. While in the Library, you may spend 1 minute searching through the books to find some piece of knowledge that you know, but may have forgotten. This knowledge is not absolute, and is affected by your own perceptions of the event witnessed or piece of knowledge learned. After searching for information in this way, you may roll an associated Intelligence check with Advantage.

Your reading speed also doubles supernaturally. At 10th Level, your reading speed triples. At 17th Level, your reading speed quadruples.

Shadow of the Signum Obscurus

 This large ornate book, devilish in origin, contains endless amounts of medical drawings of strange and fantastic beings, interspersed with arcane writings in a language you don't understand. The pages of the book turn constantly as if someone is looking for something within it, though the end of the book is never reached. This book, and the demiplane it resides in, disappear if you are killed. If the book is lost, you may summon it again by doing a special ritual that lasts 1 hour. When the book is summoned with a Bonus Action, a number of pages equal to your Intelligence modifier fly out and orbit around you while the book is summoned, and you may choose to have the book float in any unoccupied space within 5 feet of you. Expended Pages are regained after a Long Rest. The owner of this book can use any of the following abilities for 1 Action each, consuming one Page upon use. This book remains in the plane until dismissed, and when all Pages are consumed the book closes and cannot be opened by any means until you finish a Long Rest.

1. Ruby red flames and black tendrils momentarily consume one target creature within 60 Feet, dealing 1d10 Necrotic and 1d10 Fire damage and causing the target to make a Dexterity Saving Throw. On a success, the target takes half damage. On a failure, the target takes full damage and is Frightened until the end of your next turn. The damage increases to 2d10 Necrotic/Fire damage at Level 5, 3d10 at level 11, and 4d10 at Level 17. 
2. A target creature within 60 feet heals for half the damage they deal to a single target on their next turn (Rounded down).
3. You create a 10-foot radius sphere of magical Darkness at a target location within 60 feet. Devilish whispers and proposals for contracts can be heard inside the sphere, but not outside. This darkness lasts for 1 minute or until the book is dismissed. The darkness spreads around corners. A creature with darkvision can’t see through this darkness, and nonmagical light can’t illuminate it. The holder of this book may see through the darkness.

Infernal Secrets

Starting at 10th level, your patron extends some of her secret-keeping magics to you. As an action, you may make any target creature that learns something about you, such as your name, place of birth, the companions you travel (or have travelled) with, Etc., make an Intelligence Saving Throw against your Warlock Spell Save DC. If the creature succeeds, they remember whatever they've learned about you and are immune to this effect for 24 hours. If the creature fails, they immediately forget anything they've learned about you once they stop interacting with you or the topic changes from you. If an affected creature once again learns of you they may repeat the Intelligence Saving Throw, remembering everything they've forgotten about you on a success, or failing to remember you on a failure. This effect lasts until the creature makes it's save. Knowledge gained before this Class Feature is gained is not affected.

Revelation

Starting at 14th level, once per Long Rest, you can use an action to bestow instantaneous but complete knowledge of the inner workings of the universe to a target.

1. If used on an enemy, they immediately take 6d10 Psychic Damage, then they make an Intelligence Saving Throw. On a failure, the target is Incapacitated until the end of your next turn as they go temporarily mad from the instantaneous revelation. On a successful save, the target is not Incapacitated and can act normally.
2. If used on an ally, they gain Advantage on their next Intelligence, Wisdom, or Charisma Skill Check or Saving Throw. The ally then must make an Intelligence Saving Throw against your Warlock Spell Save DC. The ally takes 4d10 Psychic Damage on a failed save, or half as much on a successful save.