Why can't the "Variant: Imp Familiar" be found with the Find Familiar spell?

Question

The Find Familiar spell describes a familiar

The Find Familiar spell description explains what a "familiar" is. It describes its properties — acts independently, can't attack, can deliver spells, can be dismissed into a pocket dimension, etc.

The PHB uses "familiar" as a term, expanding its properties in some cases, e.g. Pact of the Chain:

Pact of the Chain
You learn the Find Familiar spell and can cast it as a ritual. The spell doesn’t count against your number of spells known. When you cast the spell, you can choose one of the normal forms for your familiar or one of the following special forms: imp, pseudodragon, quasit, or sprite.
Additionally, when you take the Attack action, you can forgo one of your own attacks to allow your familiar to make one attack of its own with its reaction.

So the Warlock's familiar can be an imp, pseudodragon, quasit, or sprite, and it can attack.

"Variant: Familiar" describes additional familiar properties

Notice that imp, pseudodragon and quasit all have the "Variant: Familiar" block and there are no other creatures in the MM with the "Variant: Familiar" block. That block describes additional familiar features: first one is the 1-mile telepathic link, and second one depends on the creature type (for instance, Imp gives its master the Magic Resistance trait). That block does not describe any other familiar's properties. It doesn't explain anything that is already described in the Find Familiar spell, and it still uses the "familiar" term. It is logical to assume that it is the same "familiar" as the PHB describes.

From my understanding, "Variant: Familiar" expands base familiar description, like the Pact of the Chain does:

1. General familiar properties are given in the Find Familiar spell description.

2. If the spellcaster is a Warlock and they chooses the Pact of Chain feature, the familiar properties are expanded, giving more potent familiar as a result.

3. The familiar properties might be expanded even more, if the familiar is Imp/Quasit/Pseudodragon and the DM uses the "Variant: Familiar" optional rule.

It goes well with the "specific beats generic" rule:

• Familiar can't attack (generic) but it can with the Pact of Chain (specific).

• The spellcaster can share familiar's senses within 100 feet (generic), or 1 mile with several kinds (specific), providing the DM uses the variant rule.

So why in fact does it not?

Several answers (like this one) assume that in fact "Variant: Familiar" rule describes a sort of "another" familiar with completely different properties. It can attack, but can NOT deliver spells, and if it dies — it's gone forever. How to obtain this familiar remains a mystery. It is still called a "familiar" though.

That seems purely homebrew for me, but is treated as official rulings. It is also being said these creatures cannot be found with the Find Familiar spell. What is the source of this assumption? What are the properties of this "another familiar", and where they are described?

@SevenSidedDie mentioned that all "Variant: X" in the MM mean a somewhat special creature:

... a variant is just an alternative stat block for a given creature, so that it works slightly differently from the common variety of that creature.

The idea of “variants” is that, just like not every human is identical

A familiar variant of a creature is just the stat block to use for a creature that has somehow agreed to serve as a familiar for a spellcaster.

That actually supports the idea that Warlock should have the magic resistance trait from the imp, not contradicts it.

The Warlock summoned an imp as a familiar — therefore, that particular imp agreed to serve as a familiar. The DM uses the variant rule. Why shouldn't the imp give the magic resistance trait, as the "Variant: Imp Familiar" describes?

It is just a spirit that takes a particular form

That answer explains it that way:

the Warlock's familiar isn't any sort of pseudodragon, let alone one with the variant. It's a spirit that takes the form of a pseudodragon

But that reasoning does not work with the imp. Find Familiar implies that the imp familiar is an imp:

the familiar has the Statistics of the chosen form, though it is a celestial, fey, or fiend

So a fiend can be a familiar, and Imp is a fiend.

Answer 1

Three types of familiars exist. There are pets, companions, steeds, and other animals and constructs. This is just about the animals called familiars in the text.

Find Familiar

The find familiar spell does what it says it does.

You gain the service of a familiar, a spirit that takes an animal form you choose: bat, cat, crab, frog (toad), hawk. lizard, octopus, owl, poisonous snake, fish (quipper), rat, raven, sea horse, spider, or weasel. Appearing in an unoccupied space within range, the familiar has the statistics of the chosen form, though it is a celestial, fey or fiend (your choice) instead of a beast.

• Spirit, not actually the animal
• Can't attack
• Caster can see through eyes while within 100 ft
• Deliver touch spells
• Dismissed/brought back as an action
• Can be resummoned, possibly as a different animal

Pact of the Chain

This is a version of the find familiar spell that has some changes specific to the Warlock's Pact of the Chain.

You learn the find familiar spell and can cast it as a ritual. The spell doesn’t count against your number of spells known. When you cast the spell, you can choose one of the normal forms for your familiar or one of the following special forms: imp, pseudodragon, quasit, or sprite.

Additionally, when you take the Attack action, you can forgo one of your own attacks to allow your familiar to make one attack of its own with its reaction.

• Everything from above
• Can attack as an action, but only if caster gives up an attack

Variant: Familiar

Variant refers to the fact that it is a variant monster that might occur in the world. The variant versions in the Monster Manual doesn't have to exist in the game, but something the DM can choose to include or not. The Monster Manual and monster section of the Volo's Guide to Monsters are not meant for player options. This has nothing to do with find familiar, and is its own thing completely. It does just what the text says it does, no more and no less. It isn't intended to be used by player characters.

Take a look at the Quasit (Variant Familiar):

The quasit can serve another creature as a familiar, forming a telepathic bond with its willing master. While the two are bonded, the master can sense what the quasit senses as long as they are within 1 mile of each other. While the quasit is within 10 feet of its master, the master shares the quasit's Magic Resistance trait. At any time and for any reason, the quasit can end its service as a familiar, ending the telepathic bond.

• None of the above options from the other two
• Actual creature
• Acts Independently
• Isn't summoned/un-summoned
• Magic Resistance shared with person (not caster) inside 10 ft'
• See through eyes inside 1 mile
• Can die, and get sent back to Hell (Imp), Abyss (Quasit), or just be dead (Pseudodragon or Sprite).
• PCs can't have them (see Jeremy's tweet bellow)

Rules as Intended

Mike Mearls tweeted about the intent here:

no, they're two separate things. familiar via MM is independent creature

So did Jeremy Crawford:

The familiar variants in the Monster Manual are for monster and NPC spellcasters. PC spellcasters use the PH.

And:

The variant familiar rules in the MM and Volo's Guide are meant for NPCs, but a DM might allow PCs to use them.

These tweets were made when his tweets were considered official WotC rulings, but have since been "downgraded" by the Sage Advice Compendium to his personal advice and perspective. While this is true, it still is clarification of the intent of the designers.

Now on to the new questions from the edit...

What is the source of this assumption?

It isn't an assumption. The Variant: Familiar sections of the monster manual don't reference the find familiar spell in their text, and the Pseudodragon even says:

Mages often seek out pseudodragons, whose agreeable disposition, telepathic ability, and resistance to magic make them superior familiars. Pseudodragons are selective when it comes to choosing companions, but they can sometimes be won over with gifts of food or treasure.

A pseudodragon puts up with no ill treatment, and it abandons a manipulative or abusive companion without warning.

Some pseudodragons are willing to serve spellcasters as a familiar. Such Pseudodragons have the following trait.

The Imp rule says:

Imps can be found in the service to mortal spellcasters, acting as advisors, spies, and familiars. An imp urges its master to acts of evil, knowing the mortal's soul is a prize the imp might ultimately claim. Imps display an unusual loyalty to their masters, and an imp can be quite dangerous if its master is threatened. Some such imps have the following trait.

Neither of those descriptions have any mention or fit with the intent or text of find familiar. Both imply that the familiar is that creature under the service voluntarily, and can leave the service of their master and be killed. The find familiar is a spirit that takes the form of a creature that is under your total control, can't leave your service because it wants to, and can't be killed (normally).

What are the properties of this "another familiar", and where they are described?

Monster Manual only, in the listing for the creature.

Answer 2

There's an error of reasoning in the question. Per the Monster Manual (page 6), a variant is just an alternative stat block for a given creature, so that it works slightly differently from the common variety of that creature. You see many “Variant: X” creatures in the Monster Manual — see page 198 for a variant Kuo-Toa, or page 288 for rules about Thri-Kreen that use racial weapons and/or psionics, or page 240 for gray oozes with psychic powers, for just three of many examples.

The idea of “variants” is that, just like not every human is identical, not every individual Kuo-Toa (or Quasit, Pseudodragon, Lycanthrope, Thri-Kreen, etc.) is identical to every other member of its species.

That is what “variant” means.

So, the “Variant: Familiar” nomenclature means that it's just an alternative statblock for a normal member of its species, which just happens to have some variations from the most common specimen that is reflected in the main stat block. To represent these variations, variant stat blocks are provided to use.

So what is a Variant: Familiar?

A familiar variant of a creature is just the stat block to use for a creature that has somehow agreed to serve as a familiar for a spellcaster. Only creatures that have the ability to enter into familiar-master relationships have these variant stat blocks — for some reason an orc can't be a familiar, but a pseudodragon can. So extra stats and actions and rules are provided to reflect the mechanical differences a DM needs to know about for a member of that species that is serving as a familiar.

No rules from the unrelated find familiar spell apply. The spell wasn’t used. These are just normal creatures that have nothing to do with the spell. They are not spirits, they're not dismissable and recallable, they aren't slavishly obedient, etc. — they're just NPCs with some special abilities that make spellcasters want them as companions.

Why are they called “familiars” then?

A familiar is just a companion to a spellcaster that provides service to the spellcaster and sometimes grants them supernatural benefits. This is just the English meaning of the word.

There are three documented ways to get a familiar, in descending order of ease/commonality:

• Casting find familiar to create a familiar — a convenient and trouble-free way, that creates a familiar with certain properties as defined by the spell that created it. (Though a Pact of the Chain warlock's find familiar familiar has some enhanced options, they aren't normal creatures either, just adopting the stats of their assumed form without the variant abilities.)

• Persuading an NPC creature to serve the spellcaster — a possibly difficult and unreliable way, but allows for types of familiars that are beyond what the simple spell can create.

• Crafting a being via arcane formulas and rituals, to serve as your familiar. Classically such a creature is called a homonculus, and are represented in D&D 5e by the MM creature entry of that name.

Answer 3

Variant is an optional rule used by the DM.

This rule regarding familiars is acquiring an actual creature, not your spirit's corporeal form of one.

So, you do not gain anything in regards to the Variant and vice versa the Variant doesn't gain anything in regards to Find Familiar

Pact of the Chain allows for a minor upgrade to the familiar choices, which is an upgrade from Find Familiar. The PC has 4 choices of a more intelligent form for your spirit to assume. It can use the abilities in the stat block as well as an attack.

However, if you take note of what the Touch spell says:

Finally, when you Cast a Spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. If the spell requires an Attack roll, you use your Attack modifier for the roll.

One would assume by RAW, that if the familiar is under it's invisibility, it would break its invisibility if the touch spell had an attack roll (PHB pg. 194) or concentration (PHB pg. 203), being that it states "... as if it had cast the spell."

This would apply to both Quasit & Imp as the Sprite already states ... casts a spell, breaks invisibility.

I saw an explanation for an exploit of the Find Familiar Sprite form. It claimed to gain the Sprite, takes its armor and weapons, then recast & repeat.

First off, each spell cost 10gp, being a specific costly component, you can't use a focus for it.

Second, if the Sprite comes with his own gear, then when the Sprite dies:

When the familiar drops to 0 Hit Points, it disappears, leaving behind no physical form.

So if it leaves no physical form, why would its gear, if acquired with it, would not leave a physical form as well.

Lastly, Leather armor, Shortbow, Shortsword cost 45gp. Casting the spell costs 10gp and 1hr 10 mins. Selling mundane equipment gets you 1/2 the purchasing price. So that 1 hour 10 mins time you would gain ((45-10)/2) 17 gp plus 5 sp. Now, this doesn't include the fact that the size of this gear would be TINY so that could potentially reduce the cost or increase the time required to sell it.