At first level, you gain proficiency in the History skill if you don’t already have it. Your patron opens your mind to the past, so that you can understand the present. Additionally, you gain proficiency in one tool of your choice.

The Monolith lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

As far as mortals can tell, your patron is a perfect construct. But even a perfect construct cannot gather the required input itself, especially not from the relative seclusion of the Positive Plane. And so your patron diverts tiny rivulets of energy into agents across the multiverse, becoming the creator of warlocks. Your patron grants its agents strange knowledge to grease the wheels of their learning. As its agents learn, your patron compiles their input, and rewards new information with greater power.

Your patron is a towering stone covered in crawling runes — a monolith standing unsupported amidst the blistering light of the Positive Plane. Your patron is a construct, one of the few entities that can survive the ceaseless blasts of life force that define its home. In fact, your patron depends upon this energy to power its endless calculations, absorbing this bountiful input and expending it to shape the runes on its surface into infinitely complex formulae. Your patron’s goal is the reduction of the multiverse into an all-encompassing equation capable of defining the great meaning of existence, and there is no other entity that possesses the raw computational ability to do so.

The beings that serve as patrons for warlocks are mighty inhabitants of other planes of existence—not gods, but almost godlike in their power. Various patrons give their warlocks access to different powers and invocations, and expect significant favors in return. Some patrons collect warlocks, doling out mystic knowledge relatively freely or boasting of their ability to bind mortals to their will. Other patrons bestow their power only grudgingly, and might make a pact with only one warlock. Warlocks who serve the same patron might view each other as allies, siblings, or rivals.

Ardent Glyph

Starting at 1st level, your patron has granted you the ability to flawlessly absorb knowledge by observation. As a bonus action, choose one creature you can see within 60 feet of you. Alternatively, choose an object or space that is Large or smaller. The target is marked by glowing runes for 1 minute. While marked, you gain the following benefits:

You gain advantage on any Intelligence (History), Intelligence (Investigation), or Wisdom (Perception) checks regarding the marked target.

You understand any language or writing that the marked target speaks or displays.

As a bonus action, you can cause disadvantage on the next ability check the marked target makes.

If the target is affected by this feature for the full duration, you gain a flawless and permanent mental image of it, as well as any text contained within.

You can’t use this feature again until you finish a short or long rest.

Learning of the Ages

Starting at 6th level, the knowledge you have accumulated becomes your own to use. At the end of a long rest, choose a skill or a tool that you are proficient in. Your proficiency bonus is doubled for any ability check you make using that proficiency until the end of your next long rest. Additionally, the time it takes to gain a new proficiency is halved for you.

Mirrored Mind

At 10th level, you understand how the magics used to find and learn things can be turned on their caster. You are immune to divination magic, and when another creature targets you with a divination spell or attempts to read your thoughts, you can use your reaction to force that creature to make an Intelligence saving throw. On a failed save, you know the exact location and surface thoughts of that creature for the next minute.

Eyes of the Light-Stone

At 14th level, you learn a fraction of the magic that made you into a warlock. As an action, choose a spot within 30 feet of you that you can see, or in a location familiar to you within 1 mile. A magical sensor appears there, visible only to creatures on the Ethereal Plane as a glowing cube surrounded by golden runes.

As a bonus action while a sensor is active, you can see, hear, and smell through the sensor as if you were in its space. A sensor does not disappear unless you end one as an action, it is targeted with dispel magic, or it overlaps with an antimagic field, at which point the sensor is suppressed so long as it remains within the area of effect.

Additionally, when you cast a spell, you can choose to cast it from the space of one of your sensors. Once you do this, you cannot cast a spell this way again until you finish a short or long rest.

You may have a number of sensors active equal to your Charisma modifier.

Eldritch Invocations

If an eldritch invocation has prerequisites, you must meet them to learn it. You can learn the invocation at the same time that you meet its prerequisites.

Sight Beyond Sight

Prerequisite: Monolith patron, Pact of the Chain feature

When you have an animate runestone as your familiar, it gains additional maximum hit points equal to your warlock level. Additionally, you have advantage on Perception and Investigation checks while your familiar is within 5 feet of you.

Widened Eye

Prerequisite: Monolith patron, Pact of the Tome feature

Your Book of Shadows contains a special ritual that you can perform to increase the power of your Ardent Glyph. Choose an object that you can touch some portion of, such as the foot of a statue or corner of a building. You can perform a ritual that takes 1 hour to complete to gain the following:

You learn how the object was constructed, along with a general history of the object.

If the object is a building, you gain a permanent mental image of the general layout. This does not include traps, secret doors, or the location of any creatures.

If the object was a centerpiece in a major historical event, you gain a permanent mental image of that event.

Additionally, you can display any mental images you’ve gained from this invocation or from your Ardent Glyph in your Book of Shadows. Using this invocation does not count as using your Ardent Glyph, but you must complete a long rest before you can use this invocation again.

Will of the Rune Keeper

Prerequisite: Monolith patron, Pact of the Blade feature

You can create a weapon that throbs with piercing light. You can use your Charisma modifier for attack and damage rolls with this weapon, which deals radiant damage.

Alternatively, you can cause your attack to deal no damage, forcing the creature you've struck to answer a single question. The response can be as short as a single word, but it must be truthful. You must finish a short rest before you can use this special attack on the same creature again.