Dopplemancer

Dopplemancy survives today only in antique adventurer's tales, or in the densest treatises of High academic circles. It names an arcane tradition founded on a single, unsettling premise; that a Wizard, with the right workings, might wear another's face, voice, and life as easily as a borrowed cloak. From that art grew a whole craft of infiltration: surveillance, deception, and quiet assassination, said to have flourished alongside the rise of magical espionage in the Dark Age. 

Historians of the Arcane insist Dopplemancy is a myth, merely another scrap of Dark Age propaganda, conjured to justify many of the era's countless executions. A favorite challenge among such Historians is a simple one: "Where, then, are the Dopplemancers?" Citing a fact in their favor: every recorded case of Dopplemancy either rests on the account of, or points directly to, anonymous persons.

Believers in Dopplemancy cite the very same fact, to make the opposite point.

Level 3: Dopplemancy Savant

Choose one spell each from the Illusion and Enchantment schools, then add them to your spellbook for free. These spells must not exceed Level 2.

In addition, whenever you gain access to a new level of spell slots in this class, you may add one spell each from the Illusion and Enchantment schools to your spellbook for free. The chosen spells must be of a level for which you have spell slots.

Level 3: Masque

You use Intelligence for all Deception and Persuasion checks. When wearing a disguise, you also use Intelligence for Performance checks to convince others that you are that person.

You gain the Disguise Self spell and may cast it without consuming a spell slot a number of times equal to your Proficiency Bonus per long rest. You may otherwise cast it using a spell slot. You always cast Disguise Self without Verbal Components.

You magically store people's Identities, called Masques. You may hold a number of Masques equal to your Intelligence modifier at one time.

When wearing a Masque, you have Expertise in Deception, Persuasion and Performance checks to sustain or leverage your disguise.

To obtain the Masque of an individual, you perform a magic study called Shadowing. Shadowing someone generates 1d4 Likeness per hour (increasing to 2d4 at Dopplemancy level 6, 2d6 at 10, 2d8 at 14). At 16 Likeness you obtain their Masque.

Shadowing. To obtain someone's Identity, you must perform deliberate study of them. This study is called Shadowing. In most cases, this will mean following them or observing them in person, close enough to hear them and see what they do in detail. Their mannerisms, writing style, quirks and speech patterns require careful attention to capture. For every uninterrupted hour of Shadowing you gain 1d4 Likeness, 16 Likeness captures their identity, with which you can emulate their voice and manner expertly.

Level 6: Perfect Nobody

When you cast Disguise Self, you may take a disguise called Perfect Nobody, always expending a Spell Slot to do so. Each observer perceives you as a different person; every version nondescript and forgettable. It suits its surroundings, generating a plausible stranger for whatever ordinary setting you're in. However, it confers no role, credential, uniform or authority; and so it is most appropriate where people expect to see strangers.

Additionally, when you cast Disguise Self to become a Masque, you now do so at-will, without consuming a spell slot or any other limiting resource.

Level 6: Masque Maneuvers

When you obtain a Masque, you gain one Maneuver tied to it; a spell of a level you can cast, or a discrete activatable ability the individual possesses that takes an action, bonus action, or reaction to use (such as a Fighter's Action Surge or a creature's breath weapon). It can't be a passive trait or any always-on benefit.

If you've witnessed the individual use a qualifying spell or ability, you may choose that Maneuver; otherwise, one is rolled at random from those they possess that you could cast or perform. Each Masque holds one Maneuver, usable once per long rest and only while you wear that Masque; Maneuvers consume no other resource.

You perform a Maneuver using your own statistics: your spell save DC, your spell attack bonus, and Intelligence as the spellcasting ability, regardless of the original owner's. Any feature of a Maneuver that scales (such as with caster or character level) uses yours.

Level 6: Ensemble

Whenever you cast Disguise Self, you may Ensemble up to three willing creatures, granting them the effects of Disguise Self. One Level-1 Spell Slot is consumed for each Ensembled creature; alternatively, a single Spell Slot of Level 2 or higher Ensembles up to three creatures at once. These Ensemble Disguises are of the standard Disguise Self variety, with no benefits from Dopplemancer features.

Level 10: Second Skin

When you cast Disguise Self to become a Masqued individual, your disguise is now tangible and holds up to nonmagical physical scrutiny.

Level 14: Ritual of the Unbeheld

You learn a ritual that imbues a single Masque with lasting protection against magical detection. The ritual consumes exorbitant material components whose cost scales nonlinearly with the duration and grade you choose; ranging from an expense only the wealthy could bear, up to the scale of entire corporations or industries.

The ritual produces one of two results, each lasting a duration of your choice from 1 to 7 days; greater durations cost disproportionately more.

• Unscrying Masque. Performed in any dedicated ritual space you control. While you wear this Masque, you benefit from the Nondetection Spell; the disguise cannot be found, targeted, or pierced by Divination magic, nor perceived through scrying sensors.
• Unbeholding Masque. Performed only in your fully established Wizard Tower, this grants Peerless Nondetection: all the protection of an Unscrying Masque, and in addition your disguise resists even Truesight (see below). If you perform the ritual at its maximum 7-day duration, the Truesight defense is especially potent, as noted in the status.

A Masque can hold only one such imbuement at a time. When the duration ends, the imbuement simply lapses and the Masque becomes an ordinary Masque again; it is not destroyed.

Peerless Nondetection (status — granted by an Unbeholding Masque)

While you wear a Masque under this effect, you benefit from the Nondetection spell, and your disguise is not automatically pierced by Truesight.

Instead, while a creature that can see you has Truesight, you must uphold your disguise against it. At the start of each of your turns, make a Deception or Performance check (your choice) to maintain the disguise against that creature:

• If the creature is not actively scrutinizing you, compare your check against its passive Perception.
• If the creature is actively attempting to discern impostors, such as a guardian posted to verify the identity of those it sees, it makes an opposing Insight check, and you must equal or exceed its result.

On a success, your disguise holds completely against that creature, and it perceives only your Masque. On a failure, the creature sees through your disguise enough to know that you are disguised ; it does not learn your true appearance or identity. Once a creature has seen through your disguise this way, you no longer roll against it; it remains aware that you are disguised for as long as it can see you.

Seeing through one disguise does not alert other creatures; each creature with Truesight contests your disguise independently.

If your Unbeholding Masque was created at its maximum 7-day duration, you make these checks with Advantage.