This feature is very unique, and can put a strain on your role as a DM. Be prepared for the vast information that this could give your characters access to. It may help to have a discussion with your player about any boundaries you would like to set on the questions that can be asked with this feature. It is best to place minimal limits on this feature, as the potential for information gain is an exciting part of this Patron, but some limitations may be necessary for the safety of the overall story.

Once you complete this ritual, you gain one level of exhaustion and cannot perform this ritual again for 7 days.

Beginning when you reach 14th level, you learn a special ritual to help access your Patron's vast knowledge in the service of yourself or another creature. This ritual may involve dried herbs, exotic incense, priceless jewels, or other items of mystical significance. The ritual takes one hour to complete, and the target of the ritual must be within 5 feet of you for the entire duration. At the end of the ritual, the target chooses 3 questions concerning the past, present, or future. Chanelling your Patron's power, you answer those questions truthfully.

When you reach 10th level, your Patron allows you to evade certain attacks. As a reaction when you are hit by an attack or included in the area of a damaging effect, you phase momentarily into the astral plane, avoiding the damage. This brief exposure to the Timeless Realm ends all spells that are currently affecting you.

You may use this feature a number of times equal to your Charisma modifier (minimum of 1). You regain all expended uses when you complete a short or long rest.

Beginning at 6th level, your Patron begins to whisper glimpses of what's to come in your ear. As a reaction when a creature you can see makes an attack roll, ability check, or saving throw you may roll a d8 and add or subtract the result from the roll.

Starting at 1st level, you have an uncanny ability to recall certain information. You gain proficiency in the Arcana, History, and Religion skills and add a bonus to those ability checks equal to your Charisma modifier (minimum of 1).

The Whisperer 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.

Some warlocks draw on the power of an ethereal, all-knowing being knowns as the Whisperer. These Whisperers can take the form of inscrutable beings of starlight, dark beings full of knowledge to sell, or simply mysterious voices on the wind.

Eldritch Invocations

The following are additional eldritch invocation options available to warlocks of the Whisperer Patron.

Book of the Seer

Prerequisites: The Whisperer Patron, Pact of the Tome

Your mysterious arcane sight expands your ability to cast certain spells. You can now inscribe magical rituals in your Book of Shadows. Choose two 1st-level divination spells or spells that have the ritual tag from any class’s spell list (the two needn’t be from the same list). The spells appear in the book and don’t count against the number of spells you know. With your Book of Shadows in hand, you can cast the chosen spells as rituals. You can’t cast the spells except as rituals, unless you’ve learned them by some other means. You can also cast a warlock spell you know as a ritual if it has the ritual tag.

On your adventures, you can add other divination or ritual spells to your Book of Shadows. When you find such a spell, you can add it to the book if the spell’s level is equal to or less than half your warlock level (rounded up) and if you can spare the time to transcribe the spell. For each level of the spell, the transcription process takes 2 hours and costs 50 gp for the rare inks needed to inscribe it. You cast these spells as rituals whether or not they have the ritual tag.

Cataloguer

Prerequisites: The Whisperer Patron, Pact of the Tome

Your Book of Shadows can now store information about the creatures of the world. Once per day you may complete a ten minute ritual at the end of which you speak the name of a creature. The following information about that creature magically appears in your Book of Shadows: its alignment, creature type and race, full name and titles, and its primary residence. Information of magical power, such as a true name, or information concealed by magic cannot be revealed in this way.

Diviner

Prerequisites: The Whisperer Patron

You gain proficiency in the herbalism kit, and may use the kit as your spellcasting focus. When you cast a divination spell using your herbalism kit as a focus with a spell slot higher than the spell's level, you may preserve the remaining levels of that spell slot. For example, if you cast detect magic with a 3rd level spell slot, you would use one level of that spell slot and would have a 2nd level spell slot remaining.

Fortune Teller

Prerequisites: 7th level, The Whisperer Patron

You learn a ritual that allows you to predict the immediate future of a creature, using items of power such as herbs, engraved bones, or special cards. This ritual takes 10 minutes, and can be completed during a short or long rest. When you complete this ritual, the target gains the Mark of the Whisperer. As a reaction when a creature with the Mark of the Whisperer makes an ability check, attack roll, or saving throw you activate the Mark, consuming it and allowing the creature to reroll that check, attack, or saving throw.

You can complete this ritual a number of times per day equal to your Charisma modifier (minimum of once). A creature can only bear one Mark of the Whisperer at a time.

Voodoo Channeler

Prerequisites: 14th level, The Whisperer Patron

The Whisperer has granted you secret knowledge of techniques to influence others. This technique requires an object that connects you to the target, such as a likeness of them, something written in their handwriting, a garment or piece of cloth that they wore, or a body part such as a lock of hair or a nail. As a reaction when you cast a spell that causes a creature to make a saving throw, you may present such an object to impose disadvantage on that saving throw.

Whispering Tethers

Prerequisites: 7th level, The Whisperer Patron, Pact of the Blade

When you summon your pact blade you may have it take the form of ethereal tendrils shaped like ropes, whips, tentacles, or wisps of smoke. You have a number of these tendrils equal to your Charisma modifier (minimum of 1) and may attack with all of them when you take the Attack action. The tendrils have a reach of 30 feet and deal 1d6 psychic damage on a hit. Each creature can only be targeted by a single tendril. When you hit a creature with a tendril you may force it to make a Charisma saving throw against your Spell Save DC. On a failure, the creature becomes entangled, reducing its speed by half. While tethering a creature, that tether cannot be used to attack another creature. The creature repeats the saving throw at the end of each of its turn, taking 1d6 psychic damage on a failure. An entangled creature breaks the tendril entangling it if it moves to a space more than 30 feet away from you, taking 2d6 psychic damage and dissipating the tendril for 1 minute, rendering it useless.